whistle blower vs whistle-blower

whistle blower and whistle-blower both are nouns.

Word	Noun	Adjective	Verb	Adverb
whistle blower	Yes	No	No	No
whistle-blower	Yes	No	No	No

As nouns, whistle blower and whistle-blower are synonyms defined as:

whistle blower and whistle-blower: an informant who exposes wrongdoing within an organization in the hope of stopping it

Other synonyms of whistle blower include whistleblower.

whistle blower (noun)	whistle-blower (noun)
an informant who exposes wrongdoing within an organization in the hope of stopping it	an informant who exposes wrongdoing within an organization in the hope of stopping it