vindicator

from WordNet (r) 3.0 (2006)

vindicator
    n 1: a person who argues to defend or justify some policy or
         institution; "an apologist for capital punishment" [syn:
         {apologist}, {vindicator}, {justifier}]

from The Collaborative International Dictionary of English v.0.48

Vindicator \Vin"di*ca`tor\, n. [LL., an avenger.]
   One who vindicates; one who justifies or maintains. --Locke.
   [1913 Webster]

from Moby Thesaurus II by Grady Ward, 1.0

22 Moby Thesaurus words for "vindicator":
      Nemesis, advocate, apologete, apologist, apologizer, avenger,
      champion, defender, guard, justifier, paladin, pleader, proponent,
      protector, revanchist, successful advocate, supporter, the Erinyes,
      the Eumenides, the Furies, upholder, whitewasher

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