The Collaborative International Dictionary of English v.0.48:
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.
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.
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.