ass vs coitus

ass and coitus both are nouns.

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

As nouns, coitus is a hypernym of ass; that is, coitus is a word with a broader meaning than ass:

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

ass (noun)	coitus (noun)
slang for sexual intercourse	sexual activity between individuals, especially the insertion of a man's penis into a woman's vagina until orgasm and ejaculation occur
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