whistle-blower

whistle-blower
    n 1: an informant who exposes wrongdoing within an organization
         in the hope of stopping it; "the law gives little
         protection to whistleblowers who feel the public has a
         right to know what is going on"; "the whistleblower was
         fired for exposing the conditions in mental hospitals"
         [syn: {whistle blower}, {whistle-blower}, {whistleblower}]