rump vs fundament

rump and fundament both are nouns.

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

As nouns, rump and fundament are synonyms defined as:

rump (noun)	fundament (noun)
the part of an animal that corresponds to the human buttocks	lowest support of a structure
the fleshy part of the human body that you sit on	the fleshy part of the human body that you sit on
fleshy hindquarters; behind the loin and above the round	the fundamental assumptions from which something is begun or developed or calculated or explained