The Collaborative International Dictionary of English v.0.48:

Abdicate \Ab"di*cate\, v. t. [imp. & p. p. Abdicated; p. pr. &
   vb. n. Abdicating.] [L. abdicatus, p. p. of abdicare; ab +
   dicare to proclaim, akin to dicere to say. See Diction.]
   1. To surrender or relinquish, as sovereign power; to
      withdraw definitely from filling or exercising, as a high
      office, station, dignity; as, to abdicate the throne, the
      crown, the papacy.
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   Note: The word abdicate was held to mean, in the case of
         James II., to abandon without a formal surrender.
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               The cross-bearers abdicated their service.
                                                  --Gibbon.
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   2. To renounce; to relinquish; -- said of authority, a trust,
      duty, right, etc.
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            He abdicates all right to be his own governor.
                                                  --Burke.
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            The understanding abdicates its functions. --Froude.
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   3. To reject; to cast off. [Obs.] --Bp. Hall.
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   4. (Civil Law) To disclaim and expel from the family, as a
      father his child; to disown; to disinherit.
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   Syn: To give up; quit; vacate; relinquish; forsake; abandon;
        resign; renounce; desert.

   Usage: To Abdicate, Resign. Abdicate commonly expresses
          the act of a monarch in voluntary and formally
          yielding up sovereign authority; as, to abdicate the
          government. Resign is applied to the act of any
          person, high or low, who gives back an office or trust
          into the hands of him who conferred it. Thus, a
          minister resigns, a military officer resigns, a clerk
          resigns. The expression, "The king resigned his
          crown," sometimes occurs in our later literature,
          implying that he held it from his people. -- There are
          other senses of resign which are not here brought into
          view.
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