The Collaborative International Dictionary of English v.0.48:

Vacate \Va"cate\, v. t. [imp. & p. p. Vacated; p. pr. & vb. n.
   Vacating.] [L. vacare, vacatum, to be empty. See Vacant.]
   1. To make vacant; to leave empty; to cease from filling or
      occupying; as, it was resolved by Parliament that James
      had vacated the throne of England; the tenant vacated the
      house.
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   2. To annul; to make void; to deprive of force; to make of no
      authority or validity; as, to vacate a commission or a
      charter; to vacate proceedings in a cause.
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            That after act vacating the authority of the
            precedent.                            --Eikon
                                                  Basilike.
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            The necessity of observing the Jewish Sabbath was
            vacated by the apostolical institution of the Lord's
            Day.                                  --R. Nelson.
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   3. To defeat; to put an end to. [R.]
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            He vacates my revenge.                --Dryden.
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WordNet (r) 3.0 (2006):

vacate
    v 1: leave (a job, post, or position) voluntarily; "She vacated
         the position when she got pregnant"; "The chairman resigned
         when he was found to have misappropriated funds" [syn:
         vacate, resign, renounce, give up]
    2: leave behind empty; move out of; "You must vacate your office
       by tonight" [syn: vacate, empty, abandon]
    3: cancel officially; "He revoked the ban on smoking"; "lift an
       embargo"; "vacate a death sentence" [syn: revoke, annul,
       lift, countermand, reverse, repeal, overturn,
       rescind, vacate]