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}]
    

20 Moby Thesaurus words for "whistle blower":
      betrayer, blab, blabber, blabberer, blabbermouth, delator, fink,
      informer, narc, peacher, snitch, snitcher, spy, squealer,
      stool pigeon, stoolie, talebearer, tattler, tattletale, telltale