hindquarters vs fundament

hindquarters and fundament both are nouns.

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

As nouns, hindquarters and fundament are synonyms defined as:

hindquarters and fundament: the fleshy part of the human body that you sit on

hindquarters (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
	the fundamental assumptions from which something is begun or developed or calculated or explained