antonym vs opposite word

antonym and opposite word both are nouns.

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

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

antonym and opposite word: 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 antonym include opposite.

antonym (noun)	opposite word (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