The Collaborative International Dictionary of English v.0.48:

Competitor \Com*pet"i*tor\, n. [L.: cf. F. comp['e]titeur.]
   1. One who seeks what another seeks, or claims what another
      claims; one who competes; a rival.
      [1913 Webster]

            And can not brook competitors in love. --Shak.
      [1913 Webster]

   2. An associate; a confederate. [Obs.]
      [1913 Webster]

            Every hour more competitors
            Flock to their aid, and still their power
            increaseth.                           --Shak.
      [1913 Webster]

WordNet (r) 3.0 (2006):

competitor
    n 1: the contestant you hope to defeat; "he had respect for his
         rivals"; "he wanted to know what the competition was doing"
         [syn: rival, challenger, competitor, competition,
         contender]