opposite word vs antonym

opposite word and antonym both are nouns.

Word	Noun	Adjective	Verb	Adverb
opposite word	Yes	No	No	No
antonym	Yes	No	No	No

As nouns, opposite word and antonym are synonyms defined as:

opposite word and antonym: a word that expresses a meaning opposed to the meaning of another word, in which case the two words are antonyms of each other

Other synonyms of opposite word include opposite.

opposite word (noun)	antonym (noun)
a word that expresses a meaning opposed to the meaning of another word, in which case the two words are antonyms of each other	a word that expresses a meaning opposed to the meaning of another word, in which case the two words are antonyms of each other