The Collaborative International Dictionary of English v.0.48:

Beggar \Beg"gar\, n. [OE. beggere, fr. beg.]
   1. One who begs; one who asks or entreats earnestly, or with
      humility; a petitioner.
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   2. One who makes it his business to ask alms.
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   3. One who is dependent upon others for support; -- a
      contemptuous or sarcastic use.
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   4. One who assumes in argument what he does not prove. --Abp.
      Tillotson.
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The Collaborative International Dictionary of English v.0.48:

Beggar \Beg"gar\, v. t. [imp. & p. p. Beggared; p. pr. & vb.
   n. Beggaring.]
   1. To reduce to beggary; to impoverish; as, he had beggared
      himself. --Milton.
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   2. To cause to seem very poor and inadequate.
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            It beggared all description.          --Shak.
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WordNet (r) 3.0 (2006):

beggar
    n 1: a pauper who lives by begging [syn: beggar, mendicant]
    v 1: be beyond the resources of; "This beggars description!"
    2: reduce to beggary [syn: beggar, pauperize, pauperise]

The Devil's Dictionary (1881-1906):

BEGGAR, n.  One who has relied on the assistance of his friends.