ass vs screwing

ass and screwing both are nouns.

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

As nouns, ass and screwing are synonyms defined as:

Other synonyms of ass include fuck, fucking, nookie, nooky, piece of ass, piece of tail, roll in the hay, screw, shag, shtup.

ass (noun)	screwing (noun)
slang for sexual intercourse	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