Thesauri:

		Thesauri are like dictionaries, but rather than providing definitions of words they generally provide alternate word choices. The most common example of a thesaurus is the kind used to identify synonyms or antonyms, such as Roget's Thesaurus; another kind of thesaurus helps users of databases, indexes and abstracts choose the best terms for conducting research in a particular resource or area of study, such as the Thesaurus of Psychological Index Terms or Thesaurus of ERIC Descriptors.