boo vs outcry

boo and outcry both are nouns.

Word	Noun	Adjective	Verb	Adverb
boo	Yes	No	Yes	No
outcry	Yes	No	Yes	No

As nouns, outcry is a hypernym of boo; that is, outcry is a word with a broader meaning than boo:

Other hypernyms of boo include call, cry, shout, vociferation, yell.

boo (noun)	outcry (noun)
a cry or noise made to express displeasure or contempt	a loud utterance; often in protest or opposition

boo (verb)	outcry (verb)
show displeasure, as after a performance or speech	utter aloud; often with surprise, horror, or joy
	shout louder than