bird vs croup

bird and croup both are nouns.

bird (noun)	croup (noun)
warm-blooded egg-laying vertebrates characterized by feathers and forelimbs modified as wings	a disease of infants and young children; harsh coughing and hoarseness and fever and difficult breathing
the flesh of a bird or fowl (wild or domestic) used as food	the part of an animal that corresponds to the human buttocks
informal terms for a (young) woman
a cry or noise made to express displeasure or contempt
badminton equipment consisting of a ball of cork or rubber with a crown of feathers

bird (verb)	croup (verb)
watch and study birds in their natural habitat