WordNet® is an online 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.
D. Oberle, B. Berendt, A. Hotho, and J. Gonzalez. Advances in Web Intelligence, First International Atlantic Web Intelligence Conference, AWIC 2003, Madrid, Spain, May 5-6, 2003, Proceedings, volume 2663 of Lecture Notes in Artificial Intelligence, page 142-154. Springer, (2003)