posterior vs rump

posterior and rump both are nouns.

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

As nouns, posterior and rump are synonyms defined as:

posterior (noun)	rump (noun)
the fleshy part of the human body that you sit on	the part of an animal that corresponds to the human buttocks
a tooth situated at the back of the mouth	the fleshy part of the human body that you sit on
	fleshy hindquarters; behind the loin and above the round

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