From the FAQ
"An ordinary thesaurus provides synonyms and near synonyms, usually only for single words, often without offering much information about when to use these terms. Try looking up the word “break” in a conventional thesaurus. Then look up “businesses are asking for tax breaks” in the Contextual Thesaurus. You will see the difference."
This appears to be quite a useful writing tool produced by Microsoft. A really wonderful device when one is searching for a variety of ways to express the same idea. -JL