English Etymology When used idiomatically, probably an allusion to a police officer blowing his or her whistle on observing a violation of the law. Verb blow the whistle (third-person singular simple present blows the whistle, present participle blowing the whistle, simple past blew the whistle, past participle blown the whistle) (idiomatic, usually with “on”) To disclose information to the public or to appropriate authorities concerning the illegal or socially harmful actions of a person or group, especially a corporation or government agency. In some jurisdictions, it is illegal