rump vs bum

rump and bum both are nouns.

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

As nouns, rump and bum are synonyms defined as:

rump (noun)	bum (noun)
the part of an animal that corresponds to the human buttocks	the fleshy part of the human body that you sit on
the fleshy part of the human body that you sit on	a vagrant
fleshy hindquarters; behind the loin and above the round	a person who is deemed to be despicable or contemptible
	person who does no work

rump (adjective)	bum (adjective)
	of very poor quality; flimsy

rump (verb)	bum (verb)
	ask for and get free; be a parasite
	be lazy or idle