copulation vs ass

copulation and ass both are nouns.

Word	Noun	Adjective	Verb	Adverb
copulation	Yes	No	No	No
ass	Yes	No	No	No

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

copulation: 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

copulation (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