The compound noun 'whistle-blower' is a modern metaphorical creation from the mid-20th century. It literally describes 'one who blows a whistle', directly invoking the image of a referee or police officer using a whistle to signal a foul or stop play. This vivid metaphor was applied to individuals within an organization who expose wrongdoing, effectively 'sounding the alarm'. The term's logic lies in this analogy: just as a whistle stops action on a field, the whistle-blower's revelation aims to halt illicit activities, with 'blower' clearly identifying the person who performs the act of disclosure.

Structure: whistle (sound) + blower (one who produces) whistle: From Old English hwistlian (to make a whistling sound), of imitative origin. Functions as a noun/verb root representing the act of producing a sharp, high-pitched sound. blower: From Old English blāwan (to blow). The agent noun suffix -er (one who performs an action) is attached to the verb 'blow'. It functions as an agent noun meaning 'one who blows or produces (a whistle sound)'.