ass vs hindquarters

ass and hindquarters both are nouns.

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

As nouns, ass and hindquarters are synonyms defined as:

ass (noun)	hindquarters (noun)
slang for sexual intercourse	the part of an animal that corresponds to the human buttocks
hardy and sure-footed animal smaller and with longer ears than the horse	the fleshy part of the human body that you sit on
the fleshy part of the human body that you sit on
a pompous fool