WordNet
I installed WordNet on my PC and found it very interesting in many ways. Just in case you do not know about this, according to Wikipedia "WordNet is a semantic lexicon for the English language. It groups English words into sets of synonyms called synsets, provides short, general definitions, and records the various semantic relations between these synonym sets. The purpose is twofold: to produce a combination of dictionary and thesaurus that is more intuitively usable, and to support automatic text analysis and artificial intelligence applications. The database and software tools can be downloaded and used freely." You can download the software from this site