free love vs adultery

free love and adultery both are nouns.

Word	Noun	Adjective	Verb	Adverb
free love	Yes	No	No	No
adultery	Yes	No	No	No

As nouns, adultery is a hyponym of free love; that is, adultery is a word with a more specific, narrower meaning than free love:

free love: sexual intercourse between individuals who are not married to one another
adultery: extramarital sex that willfully and maliciously interferes with marriage relations

Other hyponyms of free love include criminal conversation, fornication, fornication.

free love (noun)	adultery (noun)
sexual intercourse between individuals who are not married to one another	extramarital sex that willfully and maliciously interferes with marriage relations