National Institutes of Health thesaurus. Provides resource for medical, social, and demographic terms related to alcohol and drug use.

Getty's terms, as used in several AAT indexes.

Hierarchical and alphabetical interface to library-related terms.

You can search for a name from its meanings. The site has more than 10,000 names with meanings.

Extensive listings for chemistry. Produced by Chemical Abstracts Service, a division of the American Chemical Society.

A British business education thesaurus with an intriguing navigational component from the London Business School.

European Union terminology. Available on most European Union languages.

Structured vocabulary of place names.

A comprehensive list of LOC Classification schedules.

Links to multiple LOC thesauri, including GLIN, the Global Legal Information Network.

Definitions of common mathematical terms, along with broader, narrower, and related concepts.

National Aeronautics and Space Administration Thesaurus. Extensive coverage of scientific terms.

Astronomical terms. Searches may be performed in English, French, German, Italian, and Spanish.

Over a thousand instruments, with relational links based on the Library of Congress Subject Headings.