ass vs piece of tail

ass and piece of tail both are nouns.

Word	Noun	Adjective	Verb	Adverb
ass	Yes	No	No	No
piece of tail	Yes	No	No	No

As nouns, ass and piece of tail are synonyms defined as:

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

ass (noun)	piece of tail (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