dirty word vs rear end

dirty word and rear end both are nouns.

Word	Noun	Adjective	Verb	Adverb
dirty word	Yes	No	No	No
rear end	Yes	No	No	No

dirty word (noun)	rear end (noun)
an offensive or indecent word or phrase	the fleshy part of the human body that you sit on
a word that is considered to be unmentionable