The Collaborative International Dictionary of English v.0.48:

Overcome \O`ver*come"\, v. t. [imp. Overcame; p. p.
   Overcome; p. pr & vb. n. Overcoming.] [AS. ofercuman. See
   Over, Come, and cf. Supervene.]
   [1913 Webster]
   1. To get the better of; to surmount; to conquer; to subdue;
      as, to overcome enemies in battle.
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            This wretched woman overcome
            Of anguish, rather than of crime, hath been.
                                                  --Spenser.
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   2. To overflow; to surcharge. [Obs.] --J. Philips.
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   3. To come or pass over; to spread over. [Obs.]
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            And overcome us like a summer's cloud. --Shak.
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   Syn: To conquer; subdue; vanquish; overpower; overthrow;
        overturn; defeat; crush; overbear; overwhelm; prostrate;
        beat; surmount. See Conquer.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Overcome \O`ver*come"\, v. i.
   To gain the superiority; to be victorious. --Rev. iii. 21.
   [1913 Webster]

WordNet (r) 3.0 (2006):

overcome
    v 1: win a victory over; "You must overcome all difficulties";
         "defeat your enemies"; "He overcame his shyness"; "He
         overcame his infirmity"; "Her anger got the better of her
         and she blew up" [syn: get the better of, overcome,
         defeat]
    2: get on top of; deal with successfully; "He overcame his
       shyness" [syn: overcome, get over, subdue, surmount,
       master]
    3: overcome, as with emotions or perceptual stimuli [syn:
       overwhelm, overpower, sweep over, whelm, overcome,
       overtake]
    4: overcome, usually through no fault or weakness of the person
       that is overcome; "Heart disease can get the best of us"
       [syn: get the best, have the best, overcome]