Feature Type Thesaurus - thesaurus of terms used to categorize geographic places and features in the Alexandria Digital Library Gazetteer. Getty Art and Architecture Thesaurus - searchable database and research tool of concepts related to art, architecture, and material culture. Includes styles and periods, agents, built works, materials and techniques, and more. Getty Thesaurus of Geographic Names - search on place and feature names worldwide.
Results identify location contextually, ie what state or province a city is in, and by coordinates.
Non-preferred terminology covers variant spellings. Lexical FreeNet - this program allows you to search for rhymes and relationships between words and concepts that might never have occurred to you. NASA Thesaurus - contains the authorised subject terms by which the documents in the NASA STI databases are indexed and retrieved. Phrase Finder, The - thesaurus of phrases and sayings in English. Type in a word and it will return a list of related phrases.