bird vs boo

bird and boo both are nouns.

As nouns, bird and boo are synonyms defined as:

Other synonyms of bird include raspberry, hiss, razz, razzing, hoot, snort, Bronx cheer.

bird (noun)	boo (noun)
warm-blooded egg-laying vertebrates characterized by feathers and forelimbs modified as wings	a cry or noise made to express displeasure or contempt
the flesh of a bird or fowl (wild or domestic) used as food
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)	boo (verb)
watch and study birds in their natural habitat	show displeasure, as after a performance or speech