INGRID Library Thesaurus Allows direct term search with results hyperlinked to broader and narrower search terms. Available in English and Estonian.
Historical Thesaurus of English Contains the vocabulary of English from the earliest written records to the present, with known recorded dates of usage, taken from the Oxford English Dictionary.
Phrases Thesaurus A resource for writers. Enter a single word and it will return a list of phrases and sayings that are related to the word in some way. In English.
HASSET Provides direct term search followed by hierarchical and other types of browsing. Based on a UNESCO thesaurus.
Lexical Freenet Search for relationships between words and concepts that might never have occurred to you before.
Thinkmap Visual Thesaurus Interactive dictionary and thesaurus using a visual display for data navigation.
WordNet - a Lexical Database for English An on-line lexical reference system whose design is inspired by current psycholinguistic theories of human lexical memory. English nouns, verbs, adjectives and adverbs are organized into synonym sets, each representing one underlying lexical concept. Different relations link the synonym sets. From the Cognitive Science Laboratory, Princeton University
