stool pigeon vs stoolpigeon

stool pigeon and stoolpigeon both are nouns.

Word	Noun	Adjective	Verb	Adverb
stool pigeon	Yes	No	No	No
stoolpigeon	Yes	No	No	No

As nouns, stool pigeon and stoolpigeon are synonyms defined as:

stool pigeon and stoolpigeon: someone acting as an informer or decoy for the police

Other synonyms of stool pigeon include canary, fink, sneak, sneaker, snitch, snitcher, stoolie.

stool pigeon (noun)	stoolpigeon (noun)
a dummy pigeon used to decoy others	someone acting as an informer or decoy for the police
someone acting as an informer or decoy for the police