carnal knowledge vs ass

carnal knowledge and ass both are nouns.

Word	Noun	Adjective	Verb	Adverb
carnal knowledge	Yes	No	No	No
ass	Yes	No	No	No

As nouns, ass is a hyponym of carnal knowledge; that is, ass is a word with a more specific, narrower meaning than carnal knowledge:

carnal knowledge: sexual activity between individuals, especially the insertion of a man's penis into a woman's vagina until orgasm and ejaculation occur
ass: slang for sexual intercourse

carnal knowledge (noun)	ass (noun)
sexual activity between individuals, especially the insertion of a man's penis into a woman's vagina until orgasm and ejaculation occur	slang for sexual intercourse
	hardy and sure-footed animal smaller and with longer ears than the horse
	the fleshy part of the human body that you sit on
	a pompous fool