- Arts, Humanities & Social Sciences
- Arts, Architecture, Archaeology
- Business and Economics
- Education
- Ethnography, Linguistics
- Genealogy, Family Names
- Law
- Media
- Music, Dance, Theater
- Psychology
- Religion, Mythology, Philosophy
- Sociology, Political Science
- Transportation
- Geography & Geographic Names
- A-D
- E-Q
- R-Z
- Natural Sciences
- General
- Amphibians and Reptiles
- Anatomy
- Aquatic Invertebrates
- Biology
- Birds
- Botany, Horticulture, Forestry
- Fishes
- Geology
- Insects, Arachnids, Terrestrial Arthropods
- Mammals
- Meteorology
- Microbiology
- Mineralogy
- Oceanography
- Paleontology
- Parasitology
- Dictionaries & Thesauri
Gateways, English Language, Social Sciences and Humanities, Science & Technology - Health Sciences & Medicine
- Physical Sciences & Mathematics
- Astronomy
- AREA STUDIES
General, Alaskana, American Studies, Australian & New Zealand Studies, British Studies, Canadian Studies, Middle Eastern & North African Studies, Polar Studies - Technology, Home Economics, Military & Naval Science & History
- Encyclopedias
Area Studies Reference Sources - see also Geography & Geographic Names Reference Sources (external link)
General
- Country Studies - from Library of Congress
- Index Mundi (external link)
- The World Factbook - from the CIA
Alaskana
- Alaska Native Knowledge Network (external link)
- Alaskool Central (external link)
- Hubert Wenger Eskimo Database (external link)
- State of Alaska Home Page (external link)
American Studies
- Aboriginal Links: Canada & U.S. (external link)
- Indian Entities Recognized and Eligible to Receive Services from the United States Bureau of Indian Affairs (external link)
- Native American Ethnobotany: A Database of Foods, Drugs, Dyes, and Fibers of Native American Peoples, Derived from Plants (external link)
- The Reader's Companion to American History (external link)
Australian and New Zealand Studies
- AIATSIS Subject Thesaurus (external link) (PDF)
- APAIS Thesaurus (external link) - from Australian Public Affairs Information Service
- Australian History on the Internet (external link)
- Australian History Timelines (external link)
- Australian Literature on the Internet (external link)
- Australian Periodical Publications 1840-1845 (external link) - digital library of Australian journals that began publication between 1840-1845
- Australian Pictorial Thesaurus (external link)
- Australian Science and Technology on the Internet (external link)
- Australian Thesaurus of Education Descriptors (external link)
- Australian War Memorial Online Encyclopedia (external link)
- Dictionary of New Zealand Biography (external link)
- Encyclopedia of Australian Shipwrecks (external link)
- Guide to Australia (external link)
- Iwi-Hapū Names List (external link) - thesaurus of Māori ethnic group names from the National Library of New Zealand
- Māori Subject Headings (external link)
- New Zealand History Website (external link)
- Te Ara: The Encyclopedia of New Zealand (external link)
British Studies
- Britannia: UK Travel & British History (external link)
- British History (external link)
- Castles of Britain (external link)
- Castles of Wales (external link)
- CastleXplorer (external link) - castles of England, Scotland, and Wales
- Historical Directories (external link)
- History.uk.com (external link)
- Oxford Dictionary of National Biography (external link)
- Royal Commission on the Ancient and Historical Monuments of Wales (external link)
- Timeref.org (external link) - history of Medieval Britain
- UK Heritage (external link) - historic houses, castles, and religious sites in the United Kingdom
Canadian Studies
- Aboriginal Links: Canada & U.S. (external link)
- The Canadian Encyclopedia (external link)
- Canadian Subject Headings (external link)
- Canada's Digital Collections (external link)
- Encyclopedia of British Columbia (external link) - subscription required; free 30-day trial period
- Gazetteer of the Northwest Territories
Middle Eastern and North African Studies
Polar Studies
Arts, Humanities, and Social Science Reference Sources
Art, Architecture, Archaeology, Etc.
- Art & Architecture Thesaurus (external link)
- ArtLex Art Dictionary (external link)
- Australian Pictorial Thesaurus (external link)
- Bloomsbury Guide to Art (external link)
- Castles of Britain (external link)
- Castles of the World (external link)
- Castles of Tuscany - Alphabetical Castles Index (external link)
- Castles of Wales (external link)
- CastleXplorer (external link) - castles of England, Scotland, and Wales
- Cities and Buildings Database (external link)
- Castles of Wales (external link)
- Defence of Britain Thesaurus (external link)
- eHRAF Collection of Archaeology (external link) - requires membership or password; free trial available
- Emporis Buildings: International Database about Buildings, Construction, and the Real-Estate Industry (external link)
- English Heritage Archaeological Sciences Thesaurus (external link)
- English Heritage Building Materials Thesaurus (external link)
- English Heritage Components Thesaurus (external link)
- English Heritage Evidence Thesaurus (external link)
- English Heritage Historic Aircraft Type Thesaurus (external link)
- English Heritage Maritime Cargo Types Thesaurus (external link)
- English Heritage Maritime Craft Types Thesaurus (external link)
- English Heritage Monument Type Thesaurus (external link)
- English Heritage Object Type Thesaurus (external link)
- Grove Art Online (external link) - subscription required; free trial available
- Structurae: International Database and Gallery of Structures (external link) - structural engineering database on bridges, tunnels, dams, skyscrapers, stadiums, towers. etc., from Ancient Egypt and Rome to the present
- The Perseus Digital Library (external link) - classical art and archaeology
- Thesaurus for Graphic Materials I: Subject Terms
- Thesaurus for Graphic Materials II: Genre and Physical Characteristic Terms
- UK Heritage (external link) - historic houses, castles, and religious sites in the United Kingdom
- The Urban Conservation Glossary (external link) - glossary of the built environment
Business and Economics
- Accounting Terminology Guide (external link)
- Deposits.org Dictionary (external link)
- Encyclopedia of American Industries (external link)
- Encyclopedia of Business (external link)
- Encyclopedia of Management (external link)
- Encyclopedia of Small Business (external link)
- Encyclopedia of the New Economy (external link)
- Financial Dictionary (external link)
- Glossary of E-Commerce Terms (external link) - select Press Room from menu
- Glossary Index - from U.S. Dept. of Commerce, Bureau of Economic Analysis
- Glossary of Insurance & Financial Planning Terms (external link)
- Glossary of Insurance Terms (external link) - from Insure.com
- Glossary of Risk Management & Insurance Terms (external link)
- Insurance Dictionary (external link)
- Investopedia.com Financial Dictionary (external link)
- InvestorWords (external link)
- STW Thesaurus for Economics (external link)
- The WashingtonPost.com Business Glossary (external link)
Education
- Australian Thesaurus of Education Descriptors (external link)
- ERIC Database - includes access to the ERIC Thesaurus
- Schools Online Thesaurus
Ethnography, Linguistics, Etc.
- Aboriginal Links: Canada & U.S. (external link)
- AIATSIS Language Thesaurus (external link) (PDF)
- American Indian Resource Directory (external link)
- Atlas of the World's Languages in Danger of Disappearing Online (external link)
- Database of the Linguasphere Register (external link) - links to resources on languages of the world from the Linguasphere Observatory
- Demonyms: Names of Nationalities (external link)
- Encyclopaedia of the Orient (external link)
- Ethnologue: Languages of the World (external link)
- Global Glossary (external link) - from Classics Technology Center
- Glossary of Linguistic Terms (external link)
- Indian Entities Recognized and Eligible to Receive Services from the United States Bureau of Indian Affairs (PDF)
- Iwi-Hapū Names List (external link) - thesaurus of Māori ethnic group names from the National Library of New Zealand
Genealogy, Family Names, Etc.
- Australian Family History and Genealogy on the Internet (external link)
- Jerry Hill Presents Names (external link)
- RootsWeb.com (external link)
- The USGenWeb Project (external link)
Law
- Criminal Justice Brief, 6E: Glossary (external link)
- Criminal Justice Today, 8E: Glossary (external link)
- Criminal Law Today, 2E: Glossary (external link)
- Criminology Today, 4E: Glossary (external link)
- Duhaime's Law Dictionary (external link)
- Everybody's Legal Dictionary (external link) - from Nolo
- Glossary of Conflict of Laws (P.I.L.) Terms (external link)
- Glossary of Maritime Law Terms (external link)
- Jurisdictionary (external link)
- law.com Dictionary (external link)
- Law Dictionary (external link) - from WWLIA Legal Information Services
- The 'Lectric Law Library's Legal Lexicon's Lyceum (external link)
- Legal Dictionaries (external link) - from Jurist web site (University of Pittsburgh School of Law)
- Legal Dictionary (external link) - from LawInfo.com
- Legislative Indexing Vocabulary
Library Science
Media (Film, Radio, Television, Etc.)
- A Glossary of Film Terms (external link)
- Internet Movie Database Film Glossary (external link)
- Radio Form/Genre Terms Guide
- The Moving Image Genre-Form Guide
Music, Dance, and Theater
- Ballet Dictionary (external link)
- David's Glossary of Theatre Terms (external link)
- Diaspora Dictionary (external link) - In 3 parts (A to I) (external link) (J to Q) (external link) (R to Z) (external link)
- Encyclopedia of Music in Canada (external link)
- A Glossary of Popular Music Terms (external link)
- Glossary of Technical Theatre Terms (external link)
- Grovemusic.com (external link) - access to The New Grove Dictionary of Music and Musicians and The New Grove Dictionary of Opera (subscription required; free trial available)
- Internet Broadway Database (external link)
- Music Dictionary (external link)
- Music Dictionary (external link) - part of Dolmetsch Online (external link)
- Online Lexicon of Music. Terms of the Music Theory with Audio Samples (external link) - Based on the book "Tonal Music. Anatomy of the musical Aesthetics" by Franz Sauter
- Online Music Resources (external link) - from University of Washington Music Library
- Solomon's Glossary of Technical Music Terms (external link)
- Virginia Tech Multimedia Music Dictionary (external link)
- Yahoo! Music Dictionaries (external link)
Psychology
- Encyclopedia of Psychology (external link)
- A Glossary of Psychological Terms (external link)
- Online Dictionary of Mental Health (external link)
- Psychology Dictionary (external link)
- Psychology Glossary (external link)
- University of Alberta Cognitive Science Dictionary (external link)
- Visionary: A Dictionary for the Study of Vision (external link)
Religion, Mythology, Philosophy
- Bible Study Tools (external link)
- The Catholic Encyclopedia (external link)
- The Dictionary of Philosophical Terms and Names (external link)
- Dictionary of Philosophy of Mind (external link)
- Dictionary of Symbolism (external link)
- Digital Dictionary of Buddhism (external link)
- Easton's 1897 Bible Dictionary (external link)
- The Encyclopedia Mythica (external link)
- Internet Encyclopedia of Philosophy (external link)
- The Ism Book (external link)
- JewishEncyclopedia.com (external link) - complete contents of the 12-volume Jewish Encyclopedia, originally published 1901-1906
- The Jewish Virtual Library (external link)
- Mythical-Folk: An On-line Encyclopedia of Mythology and Folklore (external link)
- Overview of World Religions (external link)
- Stanford Encyclopedia of Philosophy (external link)
Sociology, Political Science
- iAmericanSpirit Political Dictionary (external link)
- Glossary of Congressional and Legislative Terms (external link)
- Political Dictionary (external link)
- Senate Glossary
- United States Campaign Finance Glossary (external link)
- United States Political Glossary (external link)
Transportation
Dictionaries and Thesauri
Gateways
- Encyberpedia Dictionaries, Glossaries, and Thesauri (external link)
- Glossaries, Dictionaries, and Encyclopedias: General (external link)
- The Glossarist (external link) - directory of glossaries and topical dictionaries
- Terminology Collection Online Dictionaries (external link)
- Yahoo! Subject Dictionaries (external link)
- YourDictionary.com (external link)
English Language
- American Heritage Dictionary of the English Language (external link)
- Cambridge Dictionaries Online (external link)
- Heinle's Newbury House Dictionary of American English (external link)
- Infoplease Dictionary (external link)
- Merriam-Webster Online (external link)
- OneLook Dictionary Search (external link)
- Oxford English Dictionary Online (external link) - requires subscription
- Oxford Reference Online: English Dictionaries & Thesauruses (external link) - requires subscription
- Roget's II: The New Thesaurus (external link)
- UNBIS Thesaurus (external link) - United Nations Bibliographical Information System
- USAID Thesaurus (PDF)
Social Sciences and Humanities
- APAIS Thesaurus (external link) - from Australian Public Affairs Information Service
- Art & Architecture Thesaurus (external link)
- Australian Thesaurus of Education Descriptors (external link)
- English Heritage Thesauri (external link)
- ERIC Thesaurus
- Eurovoc Thesaurus (external link)
- Family Thesaurus Online [Word : 640 KB]
- Felix Posen Bibliographic Project on Antisemitism Thesaurus (external link)
- International Thesaurus of Refugee Terminology (external link)
- National Criminal Justice Thesaurus
- Population Multilingual Thesaurus (external link)
- Transportation Research Thesaurus (external link)
- VOCED Thesaurus (external link) - from National Centre for Vocational Education Research
Science and Technology - see also specific discipline lists
- AGROVOC Thesaurus (external link)
- Engineering Dictionary (external link)
- FireTalk (external link) - from Illinois Fire Service Institute
- Glossary of Water Resource Terms (external link)
- Joint Thesaurus (external link) (PDF) - for the Energy Technology Data Exchange (ETDE) and the International Nuclear Information System (INIS)
- Life Sciences Dictionary (external link)
- Mathematics Subject Classification (external link)
- McGraw-Hill Dictionary of Scientific and Technical Terms (external link) - subscription to AccessScience required; free sample search and 30-day trial available
- NAL Agricultural Thesaurus
- Physics and Astronomy Classification Scheme (PACS) (external link)
- UCMP Glossary (external link) - for biology and paleontology, from University of California, Berkeley Museum of Paleontology
- U.S. Geological Survey Library Classification System
Encyclopedias
General
- The Columbia Electronic Encyclopedia (external link) - from AllRefer.com (external link)
- Columbia Encyclopedia (external link) - from Bartleby.com (external link)
- Encyclopedia.com (external link)
- Encyclopædia Britannica (external link) - subscription required; free trial available
- Grolier Online (external link) - subscription required; free trial available
- Infoplease Encyclopedia (external link) - articles from the Columbia Encyclopedia
- Wikipedia, The Free Encyclopedia (external link)
- World Book Online (external link) - subscription required; free trial available
Science and Technology
- McGraw-Hill Encyclopedia of Science & Technology (external link) - subscription to AccessScience required; free sample search and 30-day trial available
Geography and Geographic Names Reference Sources
Geography
- Fundamentals of Physical Geography (external link)
- Glossary of Cartographic Terms (external link)
- PhysicalGeography.net Glossary of Terms (external link)
- Standardization of Undersea Feature Names: Guidelines, Proposal Form, Terminology (external link) (PDF) (English/French version) - also available in English/Spanish version (external link) (PDF)
Geographic Names
Worldwide | Africa-Belgium | Canada | Central Europe-France | Geologic Names | Great Britain
India-Norway | Pitcairn Island-Switzerland | United States
Worldwide
- Dictionnaire de géographie ancienne et moderne à l'usage du libraire et de l'amateur de livres (external link) - published in 1870
- Directory of Cities and Towns in the World (external link)
- English Heritage Maritime Place Name Thesaurus (external link)
- Finnish Place Names Outside Finland (external link)
- A Gazetteer of the Roman World (external link)
- GEBCO Gazetteer of Undersea Feature Names (external link) (PDF)
- Geographic Names Database (external link)
- GEOnet Names Server (external link)
- Getty Thesaurus of Geographic Names (external link)
- Global Gazetteer (external link)
- Index Mundi (external link)
- Jerry Hill Presents Names (external link) - scroll down to Place Names
- The List of Wetlands of International Importance (external link) - in PDF and Microsoft Word (external link) formats
- NSS Geo2 Long & Deep Cave Lists (external link)
- National Geographic Map Machine (external link)
- Orbis Latinus Online (external link)
- Peakbagger.com (external link) - information and statistics about the mountain peaks and mountain ranges of the world
- Peakware World Mountain Encyclopedia (external link)
- The Probert Encyclopaedia Gazetteer (external link)
- Protectedplanet.net - search interface for the World Database on Protected Areas
- The Ramsar List of Wetlands of International Importance (external link)
- The Ramsar Sites Database (external link)
- Show Caves of the World (external link)
- Volcano World (external link)
- Volcanoes of the World (external link)
- Wiktionary Appendix: Place Names (external link)
- World Database on Protected Areas (external link)
- World Gazetteer (external link)
- World Heritage List (external link)
- World Lakes Database (external link)
- Yahoo! Parks and Public Lands (external link)
Africa
Antarctica
- Antarctic Gazetteer (external link)
- Antarctica - part of Geographic Names Information System
- Composite Gazetteer of Antarctica (external link)
- Verzeichnis deutschsprachiger geographischer Namen der Antarktis (external link) = Index of German-Language Antarctic Place-Names
Asia
- Old World Trade Routes (OWTRAD): A Catalogue of Georeferenced Caravanserais/Khans (external link)
- Old World Trade Routes (OWTRAD): From Afrosiab to Zucchabar: A Gazetteer of Georeferenced Nodes of Long-Distance Communication Routes (external link)
Australia
- AIATSIS Place Thesaurus (external link) (PDF) from Australian Institute of Aboriginal and Torres Strait Islander Studies
- Atlas of South Australia (external link)
- Australian Gazetteer (external link)
- Bonzle Digital Atlas of Australia (external link)
- Geographical Names Register of NSW (external link)
- Geoscience Australia Place Name Search (external link)
- History of Country Town Names (external link) - Western Australia
- Karst Index Database (external link)
- List of All Parks & Reserves in NSW (external link)
- NT Atlas and Spatial Directory (external link)
- OzEstuaries (external link)
- Place Names Register – Place Names Committee for the Northern Territory (external link)
- PlaceNames Online: South Australian State Gazetteer (external link)
- Queensland Place Names Search (external link)
Belgium
Brazil
Canada - see also North America
- The Atlas of Canada (external link)
- BC Geographical Names Search (external link)
- Canadian Geographical Names Data Base (external link)
- GeoNames Ontario: Ontario's Geographic Names Database (external link)
- GeoGratis (external link)
- Newfoundland and Labrador Abandoned Communities Index
- Northwest Territories Tourism & Parks General Park Services (external link)
- Northwest Territories Official Community Names (external link) (PDF)
- Nova Scotia Geographical Names (external link)
- Ontario Locator (external link)
- Parks Canada (external link)
- Place Names in the Vicinity of Mount Robson (external link)
- Regina, the Street Where You Live: The Origins of Regina Street Names
- Northwest Waterfall Survey (external link)
Central Europe
Costa Rica
Eastern Europe
Estonia
- KNAB: The Place Names Database of EKI (external link)
- Lists of Place Names (external link)
- Tallinna tänavanimed = Street Names of Tallinn (external link)
Europe
- Europe: Forms of Place Names (external link)
- A Jacobite Gazetteer (external link) - lists European sites connected with the Stuart kings-in-exile as well as sites connected with their lineal heirs up to the present day; includes sites in Austria, Czech Republic, France, Germany, Hungary, Italy, Slovenia, and Vatican
France
- Chercher une carte en France (external link)
- Dictionnaire topographique du département d'Eure-et-Loir, comprenant les noms de lieu anciens et modernes (external link)
- Les lieux-dits de France métropolitaine (external link)
Geologic Names
- Geologic Names Lexicon (GEOLEX)
- Lexicon of Canadian Geological Names On-line (external link)
- New Zealand Stratigraphic Lexicon (external link)
Germany
- Atlas des Deutschen Reichs (external link) - reproduction of 1883 atlas
Ghana
Great Britain
- ArchSearch (external link) - Archaeology Data Service
- Castles of Britain (external link)
- Castles of Wales (external link)
- The Gaelic Landscape of Jura: Place Names and Landscape Photography (external link)
- Galloway Placenames (external link) - Scotland
- Gazetteer for Scotland (external link)
- Gazetteer of British Place Names (external link)
- Get-a-Map (external link) - from Ordnance Survey
- Landranger (external link) - search place names on Landranger maps
- Northern Ireland Buildings Database (external link)
- Northern Ireland Sites and Monuments Database (external link)
- Place Names Gazetteer (external link) - from Ordnance Survey
- Place Names of West Aberdeenshire (external link)
- Places-Names of New Cumnock (external link)
- Royal Commission on the Ancient and Historical Monuments of Wales (external link)
Himalaya Mountains Region, see South Asia
India
Ireland
- Civil Parishes and Townlands of County Donegal (external link)
- The IreAtlas Townland Data Base (external link)
- Placenames in Ireland (external link)
Italy
- Castles of Tuscany - Alphabetical Castles Index (external link)
- Churches of Italy (external link)
- A Gazetteer of Italy (external link)
- Mercator's Place Names of Italy in 1554 (external link)
- Rome (Ancient)
Japan
Luxembourg
Madagascar
Mexico
Middle East
New Zealand
- Marine Parks and Sugar Loaf Islands Marine Protected Area (external link)
- Marine Reserves A-Z (external link)
- New Zealand Gazetteer of Official Geographic Names (external link)
- New Zealand Stratigraphic Lexicon (external link)
- Official Place Names with Macrons (external link)
Nordic Countries
North Africa
North America
- Everything Muskrat - Place Names (external link)
- Columbia Gazetteer of North America (external link)
- North American Gazetteer (external link) - from AllRefer.com (external link)
Norway
Planets, see Solar System
Poland
Scandinavia, see Nordic Countries
Slovakia
Solar System
- Digital Lunar Orbiter Photographic Atlas of the Moon (external link)
- Solar System Volcanoes (external link)
- Volcanoes on Mars (external link)
Sweden
Switzerland
Ukraine
United States - see also North America
- General
- America's Byways (external link) - list of All-American Roads and National Scenic Byways
- Geologic Names Lexicon (GEOLEX)
- The United States Show Caves Directory (external link)
- U.S. Gazetteer
- Yahoo! Parks and Public Lands (external link) - information on and links for national and state parks and forests
- Alabama
- Alaska
- Arizona
- California
- Florida
- Georgia
- Georgia Place Names (external link) - by Carl Vinson Institute of Government, University of Georgia /li>
- Georgia Place-Names (external link) - by Kenneth K. Krakow
- Kentucky
- Louisiana
- Maine
- Maryland
- Massachusetts
- Michigan
- Minnesota
- Mississippi
- Montana
- Nebraska
- Nevada
- Dams Database
- Elko County Place Names (external link)
- Nevada Ghost Trains & Towns (external link) - includes sections on mining districts and places no longer listed on the official state map
- Well Log Database
- New England
- New Hampshire
- New Jersey
- New Mexico
- New York
- North Carolina
- North Dakota
- Ohio
- Oklahoma
- Oregon
- Pennsylvania
- Rhode Island
- South Carolina
- South Dakota
- Tennessee
- Texas
- Utah
- Utah Place Names (external link) - searchable version included in Utah Collections Multimedia Encyclopedia
- Vermont
- Virginia
- Washington State
- West Virginia
- Wisconsin
- Wyoming
Health Sciences and Medicine Reference Sources
- Allergy Glossary (external link)
- Chiropractic Subject Headings (external link) (PDF)
- Diabetes Dictionary (external link)
- A Dictionary of Dental Terms (external link)
- Dorland's Medical Dictionary (external link)
- AIDSinfo Glossary
- Index to Chiropractic Literature Online Subject Index (external link)
- MedFriendly (external link) - medical dictionary
- Medical Dictionary, Medical Terminology (external link)
- The Merck Manual of Diagnosis and Therapy (external link)
- The Merck Manual of Geriatrics (external link)
- MeSH Browser
- Mycology Online (external link) - guide to fungal pathogens of humans and the diseases they cause
- The Phobia List (external link)
- PubMed
- TOXNET (Toxicology Data Network)
- Visionary: A Dictionary for the Study of Vision (external link)
- WebMD (external link)
- A Web of Specialized On-line Dictionaries: Dentistry (external link) - Medicine (external link)
Natural Sciences Reference Sources
General Resources
- Animal Diversity Web (external link)
- AnimalBase (external link)
- Biology Browser (external link)
- Census of Antarctic Marine Life (external link)
- Codes for Australian Aquatic Biota (external link) - from CSIRO
- EE-Link Endangered Creatures (external link)
- eNature Field Guides (external link) - covers over 5,500 plants and animals of North America
- The Encyclopedia of Life (external link)
- EUNIS - European Nature Information System (external link)
- European Register of Marine Species (external link)
- Glossary of Biospeleology (external link)
- Index to Organism Names (external link)
- InfoNatura: Birds, Mammals, and Amphibians of Latin America (external link)
- Integrated Taxonomic Information System (ITIS)
- International Species Information System (ISIS) (external link)
- ITIS * North America (external link)
- IUCN Red List of Threatened Species (external link)
- Marine Species Database for Eastern Africa (external link)
- NatureServe Explorer: An Online Encyclopedia of Life (external link)
- NCBI Entrez Genome Project
- The NCBI Taxonomy Homepage
- NeMys (external link) - a general online species information system, with original primary focus on marine Nematoda and Mysida
- Nonindigenous Aquatic Species
- SeaLifeBase (external link)
- Species 2000 (external link)
- uBio: Universal Biological Indexer and Organizer (external link)
- WildFinder (external link) - database from World Wildlife Fund
- World Register of Marine Species (external link)
Amphibians and Reptiles
- AmphibiaWeb (external link)
- Amphibian Species of the World (external link)
- The Amphibian Tree of Life (external link)
- Checklist of Amphibian Species and Identification Guide: An Online Guide for the Identification of Amphibians in North America North of Mexico
- Checklist of the Living Monitor Lizards of the World (Family Varanidae) (external link) (PDF)
- Crocodilian Species List (external link)
- JCVI/TIGR Reptile Databases (external link)
- National Amphibian Atlas (external link)
- Reptiles and Amphibians of the World (external link)
- Scientific and Common Names of the Reptiles and Amphibians of North America Explained (external link)
- Scientific and Standard English names of Amphibians and Reptiles of North America, with Comments Regarding Confidence in Our Understanding (external link)
- Standard Common and Current Scientific Names for North American Amphibians, Turtles, Reptiles & Crocodilians (external link) (PDF)
- World Turtle Database (external link)
Anatomy
- Lower Extremity Muscle Atlas (external link)
- Master Muscle List (external link)
- Upper Extremity Muscle Atlas (external link)
Aquatic Invertebrates
- Anchialine Caves and Cave Fauna of the World (external link)
- Annelid Resources (external link)
- Aquatic Species Fact Sheets (external link)
- Brachiopoda World Database (external link)
- Cephalopods of the World (external link) (2005 edition)
- CephBase (external link) - includes list of all living cephalopod species
- Crustacea.net (external link)
- Cumacea World Database (external link)
- Current Classification of Recent Cephalopoda (external link) (PDF)
- The Echinoid Directory (external link)
- Field Guide to Freshwater Mussels of the Midwest (external link)
- Freshwater Mussel (Unionoida) Genera of the World (external link)
- Hexacorallians of the World: Sea Anemones, Corals, and Their Allies (external link)
- The Hydrozoa Directory (external link)
- Marine Flatworms of the World (external link)
- Phoronida World Database (external link)
- Phylum Ctenophora: List of All Valid Species Names (external link)
- PycnoBase: World List of Pycnogonida (external link)
- The Seafood List - U.S. Food and Drug Administration
- Stauromedusae: List of All Valid Species Names (external link)
- World Asteroidea Database (external link)
- World Database of Proseriata and Kalyptorhynchia (external link)
- World List of Marine, Freshwater, and Terrestrial Isopod Crustaceans (external link) - version on Smithsonian site
- World List of Marine, Freshwater, and Terrestrial Isopod Crustaceans (external link) - version on World Register of Marine Species site
- The World of Copepods (external link)
- World Ophiuroidea Database (external link)
- World Porifera Database (external link)
- World Remipedia Database (external link)
Biology (Genetics, Cell Biology, Molecular Biology, Etc.)
- Biology Browser (external link)
- The Encyclopaedia of Actin-Binding Proteins (and Drugs) (external link)
- Human Protein Reference Database (external link)
- Kimball's Biology Pages (external link) - an online textbook
- Primer on Molecular Genetics
- Visionary: A Dictionary for the Study of Vision (external link)
Birds
- A Field Guide to the Birds on the Web (external link)
- All About Birds (external link) - from Cornell Lab of Ornithology
- Annotated List of Shorebirds (Waders) of the World (external link)
- Annotated List of the Seabirds of the World (external link)
- Avibase: The World Bird Database (external link)
- Bird Checklists of the World (external link)
- Bird Families of the World (external link)
- BirdLife International Search for Species (external link)
- Birds of the World: A Clements-like Listing (external link)
- Birds of the World: Current Valid Scientific Avian Names (external link)
- Check-List of North American Birds (external link)
- Find a Bird Dictionary (external link) - dictionary of birdwatching and ornithological terminology
- Internet Bird Collection (external link)
- Maps & Distribution of the Birds of the Western Palearctic Region (external link)
- Multi-lingual Bird Search Engine (external link)
- Multilingual North European Bird Dictionary (external link)
- Obsolete English Names of North American Birds and Their Modern Equivalents
- The Ocean Wanderers Guide to Shorebirds (external link)
- Online Bird Guide (external link) - from Cornell Lab of Ornithology
- Owls of the World: A List by Name (external link)
- Patuxent Bird Identification InfoCenter
- Sibley and Monroe's World List of Birds (external link)
- The Sibley-Monroe Classification - List of Families (external link)
- The Sibley/Monroe World List of Bird Names (external link)
- Taxonomic Changes Since Sibley & Monroe 1993 (external link)
- The Up-to-date World List of Birds (external link)
- World Bird Database (external link) - from BirdLife International
Botany, Horticulture, and Forestry
- AlgaeBase (external link)
- AlgaTerra Information System (external link)
- Angiosperm Phylogeny Website (external link)
- Australian Plant Name Index (external link)
- Bibliography of Systematic Mycology (external link)
- Bryophyte Names Authority List (external link)
- The CABI Bioscience and CBS Database of Fungal Names (external link)
- Canadian Poisonous Plants Information System (external link)
- Checklist of World Ferns (external link)
- A Classification for Extant Ferns (external link) (PDF)
- Comprehensive Listing of Alternate and Botanical Names for Horticultural Crops (external link)
- A Cumulative Checklist for the Lichen-forming, Lichenicolous, and Allied Fungi of the Continental United States and Canada (external link)
- Dr. Duke's Phytochemical and Ethnobotanical Databases
- Electronic Plant Information Centre (ePIC) (external link) - from Royal Botanic Gardens, Kew
- The Families of Flowering Plants (external link)
- Family Names Databases (external link) - fungal family names
- Forestry (external link) - Terminology Collection Online Dictionaries
- Fungal Databases
- Gardener's Dictionary (external link) - from National Gardening Association
- GardenWeb Glossary of Botanical Terms (external link)
- A Global Compendium of Weeds (external link)
- Glossary of Forestry Terms (external link)
- Glossary of Pollen and Spore Terminology (external link)
- GrassBase: the Online World Grass Flora (external link)
- Grass Genera of the World (external link)
- GRIN Taxonomy - Germplasm Resources Information Network, USDA Agricultural Research Service
- GRIN-CA Taxonomy (external link)
- Gymnosperm Database (external link)
- Horticopia Plant List (external link)
- HortiPlex Database (external link)
- ILDIS: International Legume Database & Information Service (external link)
- ILDIS Legumes of the World (external link)
- Index of Mosses Database (W³MOST) (external link)
- Index Nominum Algarum (external link)
- Index Nominum Genericorum (external link)
- International Plant Names Index (external link)
- Kew Record of Taxonomic Literature (external link)
- Mansfeld's World Database of Agricultural and Horticultural Crops (external link)
- Multilingual Multiscript Plant Name Database (external link)
- Mycology Online (external link) - guide to fungal pathogens of humans
- MycoWeb - Mycological Links (external link)
- MycoWeb - Systematic Resources (external link)
- MyxoWeb: A Virtual Field Guide to Myxomycetes (external link)
- Names in Current Use for Extant Plant Genera (external link)
- Native American Ethnobotany: A Database of Foods, Drugs, Dyes, and Fibers of Native American Peoples, Derived from Plants (external link)
- The Plants National Database
- Plant Physiology Online (external link)
- Postcode Plants Database (external link) - information on British flora and fauna
- Provisional Global Plant Checklist (external link)
- The Seaplant Handbook (external link)
- A Synonymized Checklist of the Vascular Flora of the United States, Puerto Rico, and the Virgin Islands (external link)
- Vascular Plant Families and Genera (external link)
- Vascular Plant Image Library (external link)
- W³TROPICOS (external link) - access to the Missouri Botanical Garden's VAST nomenclatural database and associated authority files
- World Checklist of Monocotyledons (external link)
- World Checklist of Selected Plant Families (external link)
- The WWW Virtual Library: Mycology (external link)
Fishes and Fisheries
- All Catfish Species Inventory (external link)
- Aquatic Species Fact Sheets (external link)
- Atlantic and Gulf Coast Local Fish Names
- Australian Fish Names Standard (external link) (PDF)
- Catalog of Fishes (external link)
- Checklist of Living Sharks (external link)
- FAO Fisheries Glossary (external link)
- Glossary of Aquaculture (external link)
- Hawaiian Islands Local Names
- LarvalBase (external link)
- List of Animal Species Used in Aquaculture (external link)
- List of Canadian Acceptable Common Names for Fish and Seafood (external link)
- Master Index of Freshwater Fishes (external link)
- NOAA Fisheries Glossary (PDF)
- Pacific Coast Local Names
- The Seafood List< - U.S. Food and Drug Administration
- Standard Fish Names in Australia (Commercial Species) (external link)
Geology and Earth Sciences
- BGS Lexicon of Named Rock Units (external link)
- California Integrated Seismic Network (external link)
- Cave and Karst Terminology (external link) - also in another edition (external link)
- COSMOS (Consortium of Organizations for Strong-Motion Observation Systems) Virtual Data Center (external link)
- Databases and Glossaries (external link) - from Links for Mineralogists (external link)
- Earth Impact Database (external link)
- Earthquake Glossary
- Geologic Glossary
- Geologic Names Lexicon (GEOLEX)
- Geologic Time Scale (external link) - detailed chart from Geological Society of America
- The Geologic Time Scale (external link) - from U.S. Geological Survey
- Geological Time Scale (external link)
- Geologylink Geologic Glossary (external link)
- Geologynet Online Geology Databases (external link)
- GeoMan's Glossary of Earth Science Terms (external link)
- A Glossary-Dictionary-Collection of Terms-Terminology Related to the Field of Geology (external link)
- Glossary of Caving Terms (external link)
- Glossary of Karst Related Terms (external link)
- Glossary of Speleological and Caving Terms (external link)
- Glossary of Volcano and Related Terminology
- Illustrated Glossary of Geologic Terms (external link)
- Lexicon of Canadian Geological Names On-line (external link)
- A Lexicon of Cave and Karst Terminology with Special Reference to Environmental Karst Hydrology
- Maps and Lists of Current Earthquake Activity (external link)
- New Zealand Stratigraphic Lexicon (external link)
- Seismo-Watch Earthquake News and Information Services (external link)
- Sequence Stratigraphy Terminology (external link)
- Some Volcanic, Cave, and Karst Terms (external link)
- Tsunami Glossary
- USGS Earthquake Hazards Program - includes Historical Earthquakes
- USGS National Strong-Motion Program
- Glossary of Volcanic and Geologic Terms (external link)
- Volcanic and Geologic Terms (external link)
- Volcano and Hydrologic Hazards, Features, and Terminology
- Volcano World (external link)
- Volcanoes of the World (external link)
- Web Geological Time Machine (external link)
Insects, Arachnids, and Terrestrial Arthropods
- Antbase (external link)
- AntWeb (external link) - includes taxonomic database of the world's ants
- Arachnology Home Page (external link)
- Australian Insect Common Names (external link)
- Bark and Wood Boring Beetles of the World (external link)
- The BioSystematic Database of World Diptera
- BugGuide.Net: Identification, Images & Information for Insects, Spiders & Their Kin for the United States & Canada (external link)
- Butterflies and Moths of North America (external link)
- Butterflies and Moths of the World: Generic Names and Their Type-species (external link)
- Checklist of the Collembola (external link)
- Common Names of Insects & Related Organisms (external link)
- Common Names Database
- Dragonflies and Damselflies (Odonata) of the United States
- English Names of North American Butterflies Occur[r]ing North of Mexico (external link)
- The Families of Diptera (external link)
- Family-group Names for Earwigs (Dermaptera) (external link)
- Field Guide to Common Western Grasshoppers
- Fleas (Siphonaptera) (external link)
- FLOW: Fulgoromorpha Lists on the Web (external link) - online database on planthoppers (Hemiptera: Fulgoromorpha)
- A Glossary of Entomological Terms (external link)
- Hymenoptera Name Server (external link)
- Insects and Related Arthropods of North America
- LepIndex: The Global Lepidoptera Names Index (external link)
- Mayflies of the United States
- Mayfly Central (external link)
- Nomina Insecta Nearctica (external link)
- The Odonata of North America (external link)
- OdonataCentral (external link)
- Online Termite Database (external link)
- On-line Systematic Catalog of Plant Bugs (Insecta: Heteroptera: Miridae) (external link)
- Orthoptera Species File Online (external link)
- Plant Bug Planetary Biodiversity Inventory (external link)
- ScaleNet: A Database of the Scale Insects of the World
- The Scorpion Files (external link)
- The Social Insects Glossary (external link)
- Stoneflies of the United States
- TaxoDros: The Database on Taxonomy of Drosophilidae (external link)
- Tiger Beetles of the United States
- Trichoptera World Checklist (external link)
- An Updated Classification of the Recent Crustacea (external link) (PDF)
- Valid Stonefly Names for North America (external link)
- World Checklist of Extant Mecoptera Species (external link)
- World List of Marine, Freshwater, and Terrestrial Isopod Crustaceans (external link)
- World Odonata List
- The Zoraptera Database (external link)
Mammals
- Animal Info: Information on Rare, Threatened, and Endangered Mammals (external link)
- Breeds of Livestock (external link)
- A Checklist of Australian Marsupials (external link)
- Integrated Primate Biomaterials and Information Resource (IPBIR) (external link)
- Mammal Image Library of the American Society of Mammalogists (external link)
- Mammal Species of the World (external link)
- Mammalian Species (external link)
- North American Mammals (external link)
- Primate Fact Sheets (external link)
- Revised Checklist of North American Mammals North of Mexico, 2003 (external link)
Meteorology
- Glossary (external link) - from Weather Channel
- Hopkins Glossary of Weather Terms (external link)
- NOAA Tidal Terminology Reference/Dictionary (external link)
- The Weather Channel Storm Encyclopedia (external link)
Microbiology
- Amoebae on the Web (external link)
- Approved Lists of Bacterial Names (external link)
- Bacterial Nomenclature Up-to-date (external link)
- Ciliate Resource Archive (external link)
- Dictionnaire de bactériologie vétérinaire (external link)
- List of Prokaryotic Names with Standing in Nomenclature (external link)
- Microbial Biorealm (external link)
- Protist Image Data (external link)
- Protist Information Server (external link)
- Viral Biorealm (external link)
- Virology Glossary (external link)
Mineralogy
- Alphabetical Mineral Reference (external link)
- Dictionary of Mining, Mineral, and Related Terms - alternate address (external link)
- Mindat.org - The Mineral and Locality Database (external link)
- The Mineral Gallery (external link) - includes Minerals by Name (external link) and Minerals by Class (external link)
- WebMineral: Atlas minéralogique (external link) - in French
Oceanography and Water Sciences
- Glossary of Physical Oceanography and Related Disciplines (external link)
- Glossary of Water Resource Terms (external link)
- NOAA Tidal Terminology Reference/Dictionary (external link)
- Tsunami Glossary
- Water Science Glossary of Terms
Paleontology
- Dinosaur and Paleontology Dictionary (external link)
- Dinosaur Encyclopaedia (external link)
- Dinosaur Genera (external link)
- Elasmo.com : The Life and Times of Long Dead Sharks (external link) - includes list of fossil genera
- The Fossil Record 2 (external link)
- Genera and Species of Paleocene Mammals (external link)
- Glossary of Pollen and Spore Terminology (external link)
- A Guide to the Orders of Trilobites (external link)
- Palaeos: The Trace of Life on Earth (external link)
- The Paleobiology Database (external link)
Parasitology
- NEMABASE (external link)
- Nematode Species List (external link)
- Turbellarian Taxonomic Database (external link)
Physical Sciences and Mathematics Reference Sources
General
- AccessScience (external link) - McGraw-Hill Encyclopedia of Science & Technology and McGraw-Hill Dictionary of Scientific and Technical Terms (subscription required; free sample search and 30-day trial available)
Astronomy
- Astronomical Glossary (external link)
- The Astronomy Thesaurus (external link)
- Atlas of Peculiar Galaxies (external link)
- The Catalogue of Meteorites (external link)
- Cosmos: The SAO Encyclopedia of Astronomy (external link)
- Data Base of Physical and Dynamical Properties of Near Earth Asteroids (NEAs) (external link)
- ESI HST Guide Star Catalogue (external link)
- Glossary of Astronomical Terms (external link)
- Handbook of Space Astronomy and Astrophysics (external link)
- Imagine the Universe! Dictionary
- The Messier Catalog (external link)
- Meteoritical Bulletin Database - also: Quick Meteorite Name Search (external link)
- NASA/IPAC Extragalactic Database (external link)
- Physics and Astronomy Classification Scheme (external link)
- Referenced Glossary for Planetary Geology for Teachers (external link)
- SIMBAD Astronomical Database (external link)
Chemistry
- Acronym Database (external link)
- Biopesticide Active Ingredient Fact Sheets
- Chemical and Other Safety Information (external link) - including Material Safety Data Sheets (external link)
- Chemical Elements.com (external link)
- ChemIDplus
- Chemistry Dictionary (external link)
- Compendium of Pesticide Common Names (external link) - mirror site (external link)
- CRC Handbook of Chemistry and Physics (external link)
- Electrochemistry Dictionary (external link)
- Glossary of Archaic Chemical Terms (external link)
- Hazardous Chemical Database (external link)
- MSDS Provider (external link)
- SIRI MSDS Index (external link)
Mathematics, Computer Science, Information Technology
- ComputerUser High-Tech Dictionary (external link)
- Eric Weisstein's World of Mathematics (external link) - extensive dictionary
- FOLDOC: Free On-line Dictionary of Computing (external link)
- Glossary of Mathematical Terms (external link)
- Mathematics Subject Classification (external link)
- Multimedia Glossary (external link)
- NetLingo: The Internet Dictionary (external link)
- A Visual Dictionary of Special Plane Curves (external link)
- whatis.com (external link) - dictionary of computing and information technology terms
Physics
- CODATA Internationally Recommended Values of the Fundamental Physical Constants
- Dictionary of Physics (external link)
- A Dictionary of Units (external link)
- Eric Weisstein's World of Physics (external link) - extensive dictionary
- Glossary of Plasma Physics and Fusion Energy Research
- Gravity/Magnetic Glossary (external link)
- How Many? A Dictionary of Units of Measurement (external link)
- International System of Units
- The Laws List (external link)
- Physics and Astronomy Classification Scheme (external link)
- Solar Physics Glossary
Technology, Photography, Home Economics, Military and Naval Science and History Reference Sources
- ASN Aviation Safety Database (external link) - descriptions of aircraft accidents, hijackings, and other incidents since 1943
- Barkley's OASIS Comprehensive Technology Glossary (external link)
- The Cook's Thesaurus (external link)
- Digital Dictionary - A Glossary of Photographic Terms (external link)
- Engineering Dictionary (external link)
- The Food Lover's Companion (external link)
- Food Lover's Glossary (external link)
- A Glossary of Photographic Terms (external link)
- Glossary of Telecommunications Terms (external link)
- NETC [National Emergency Training Center] Thesaurus (PDF)
- Oilfield Glossary (external link) - from Schlumberger
- The Photographic Glossary (external link)
- The PhotoNotes.org Dictionary of Film and Digital Photography (external link)
- Power Engineering Dictionary (external link)
- Reader's Companion to Military History (external link)
- The Wine Lover's Companion (external link)