Synonyms and Antonyms

Synonym
A synonym is a word that means exactly the same as, or very nearly the same as, another word in the same language.
For example, "close" is a synonym of "shut".
You can find synonyms in a thesaurus.
Antonym
An antonym is a word that means the opposite of another word.
For example "good" and "bad" are antonyms.
You can find antonyms in a dictionary of antonyms.