WordNet
A large lexical database of English, developed under the direction of George A. Miller. Nouns, verbs, adjectives and adverbs are grouped into sets of cognitive synonyms ("synsets"), each expressing a distinct concept. Synsets are interlinked by means of conceptual-semantic and lexical relations. The resulting network of words and concepts can be navigated with the browser. WordNet is freely available for download. WordNet's structure makes it a useful tool for computational linguistics and natural language processing.