blackmailer

from WordNet (r) 3.0 (2006)

blackmailer
    n 1: a criminal who extorts money from someone by threatening to
         expose embarrassing information about them [syn:
         {blackmailer}, {extortioner}, {extortionist}]

from The Collaborative International Dictionary of English v.0.48

Blackmailer \Black"mail`er\, n.
   One who extorts, or endeavors to extort, money, by black
   mailing.
   [1913 Webster]

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