posterior vs fanny

posterior and fanny both are nouns.

Word	Noun	Adjective	Verb	Adverb
posterior	Yes	Yes	No	No
fanny	Yes	No	No	No

As nouns, posterior and fanny are synonyms defined as:

posterior (noun)	fanny (noun)
the fleshy part of the human body that you sit on	the fleshy part of the human body that you sit on
a tooth situated at the back of the mouth	external female sex organs

posterior (adjective)	fanny (adjective)
located at or near or behind a part or near the end of a structure
coming at a subsequent time or stage