excretion vs buttock

excretion and buttock both are nouns.

Word	Noun	Adjective	Verb	Adverb
excretion	Yes	No	No	No
buttock	Yes	No	No	No

excretion (noun)	buttock (noun)
the bodily process of discharging waste matter	either of the two large fleshy masses of muscular tissue that form the human rump
waste matter (as urine or sweat but especially feces) discharged from the body