Source : Webster's Revised Unabridged Dictionary (1913)

Vindicate \Vin"di*cate\, v. t. [imp. & p. p. {Vindicated}; p.
   pr. & vb. n. {Vindicating}.] [L. vindicatus, p. p. of
   vindicare to lay claim to, defend, avenge. See {Vengeance}.]
   1. To lay claim to; to assert a right to; to claim. [R.]

            Is thine alone the seed that strews the plain? The
            birds of heaven shall vindicate their grain. --Pope.

   2. To maintain or defend with success; to prove to be valid;
      to assert convincingly; to sustain against assault; as, to
      vindicate a right, claim, or title.

   3. To support or maintain as true or correct, against denial,
      censure, or objections; to defend; to justify.

            When the respondent denies any proposition, the
            opponent must directly vindicate . . . that
            proposition.                          --I. Watts.

            Laugh where we must, be candid where we can, But
            vindicate the ways of God to man.     --Pope.

   4. To maintain, as a law or a cause, by overthrowing enemies.
      --Milton.

   5. To liberate; to set free; to deliver. [Obs.]

            I am confident he deserves much more That vindicates
            his country from a tyrant Than he that saves a
            citizen.                              --Massinger.

   6. To avenge; to punish; as, a war to vindicate or punish
      infidelity. [Obs.] --Bacon.

            God is more powerful to exact subjection and to
            vindicate rebellion.                  --Bp. Pearson.

   Syn: To assert; maintain; claim. See {Assert}.

Source : WordNet®

vindicate
     v 1: show to be right by providing justification or proof;
          "vindicate a claim" [syn: {justify}]
     2: maintain, uphold, or defend; "vindicate the rights of the
        citizens"
     3: clear of accusation, blame, suspicion, or doubt with
        supporting proof; "You must vindicate yourself and fight
        this libel"