adultery vs free love

adultery and free love both are nouns.

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

As nouns, free love is a hypernym of adultery; that is, free love is a word with a broader meaning than adultery:

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

Other hypernyms of adultery include extramarital sex.

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