National Aeronautics and Space Administration Thesaurus. Extensive coverage of scientific terms.
Extensive listings for chemistry. Produced by Chemical Abstracts Service, a division of the American Chemical Society.
Definitions of common mathematical terms, along with broader, narrower, and related concepts.
You can search for a name from its meanings. The site has more than 10,000 names with meanings.
Getty's terms, as used in several AAT indexes.
Structured vocabulary of place names.
Links to multiple LOC thesauri, including GLIN, the Global Legal Information Network.
A comprehensive list of LOC Classification schedules.
National Institutes of Health thesaurus. Provides resource for medical, social, and demographic terms related to alcohol and drug use.
Management education thesaurus from the London Business School organizes terms into a solar system of related ideas.