A thesaurus is a book or program that lists synonyms and antonyms of words. ... The plural of thesaurus is thesauruses or thesauri. A synonym is a word that has the same meaning as another word.

Why is a thesaurus called a thesaurus?

Etymology. The word "thesaurus" comes from Latin thēsaurus, which in turn comes from Greek θησαυρός (thēsauros) 'treasure, treasury, storehouse'. ... It was Roget who introduced the meaning "collection of words arranged according to sense", in 1852.

What are the two forms of thesaurus?

There are two types of thesauri: one for general use and another for the use in specific area such as medicine, arts, music, and others. In information science, a thesaurus is a collection of controlled vocabularies which are used for indexing information.