Your Mac also comes with a versatile Dictionary application. It also includes to other reference libraries such as thesaurus, Apple glossary, and Wikipedia. With it, you can find definitions, learn of the word's origin, find synonyms and antonyms, or get encyclopedic knowledge about any subject.
The Dictionary application, developed by Apple for its Macintosh computers, was introduced with Mac OS X v10.4 "Tiger". It provides definitions and synonyms from the New Oxford American Dictionary, 2nd Edition and Oxford American Writers Thesaurus, 1st Edition.