dirty word vs piece of tail

dirty word and piece of tail both are nouns.

Word	Noun	Adjective	Verb	Adverb
dirty word	Yes	No	No	No
piece of tail	Yes	No	No	No

dirty word (noun)	piece of tail (noun)
an offensive or indecent word or phrase	slang for sexual intercourse
a word that is considered to be unmentionable