quadruped vs croup

quadruped and croup both are nouns.

Word	Noun	Adjective	Verb	Adverb
quadruped	Yes	Yes	No	No
croup	Yes	No	No	No

quadruped (noun)	croup (noun)
an animal especially a mammal having four limbs specialized for walking	the part of an animal that corresponds to the human buttocks
	a disease of infants and young children; harsh coughing and hoarseness and fever and difficult breathing

quadruped (adjective)	croup (adjective)
having four feet