The Collaborative International Dictionary of English v.0.48:

Cock \Cock\ (k[o^]k), n. [AS. coc; of unknown origin, perh. in
   imitation of the cry of the cock. Cf. Chicken.]
   1. The male of birds, particularly of gallinaceous or
      domestic fowls.
      [1913 Webster]

   2. A vane in the shape of a cock; a weathercock.
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            Drenched our steeples, drowned the cocks! --Shak.
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   3. A chief man; a leader or master. [Humorous]
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            Sir Andrew is the cock of the club, since he left
            us.                                   --Addison.
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   4. The crow of a cock, esp. the first crow in the morning;
      cockcrow. [Obs.]
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            He begins at curfew, and walks till the first cock.
                                                  --Shak.
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   5. A faucet or valve.
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   Note: Jonsons says, "The handle probably had a cock on the
         top; things that were contrived to turn seem anciently
         to have had that form, whatever was the reason."
         Skinner says, because it used to be constructed in
         forma crit[ae] galli, i.e., in the form of a cock's
         comb.
         [1913 Webster]

   6. The style of gnomon of a dial. --Chambers.
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   7. The indicator of a balance. --Johnson.
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   8. The bridge piece which affords a bearing for the pivot of
      a balance in a clock or watch. --Knight.
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   9. a penis. [vulgar]
      [PJC]

   Ball cock. See under Ball.

   Chaparral cock. See under Chaparral.

   Cock and bull story, an extravagant, boastful story; a
      canard.

   Cock of the plains (Zool.) See Sage cock.

   Cock of the rock (Zool.), a South American bird (Rupicola
      aurantia) having a beautiful crest.

   Cock of the walk, a chief or master; the hero of the hour;
      one who has overcrowed, or got the better of, rivals or
      competitors.

   Cock of the woods. See Capercailzie.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

cock of the rock \cock of the rock\, cock-of-the-rock
\cock-of-the-rock\n.
   a bird of the Andes (Rupicola peruviana) similar to
   Rupicola rupicola.

   Syn: Rupicola peruviana.
        [WordNet 1.5]

   2. tropical bird of Northern South America (Rupicola
      rupicola), the male having brilliant red or orange
      plumage and an erectile disklike crest.

   Syn: cock of the rock, Rupicola rupicola.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

cock of the rock
    n 1: bird of the Andes similar to Rupicola rupicola [syn: cock
         of the rock, Rupicola peruviana]
    2: tropical bird of northern South America the male having
       brilliant red or orange plumage and an erectile disklike
       crest [syn: cock of the rock, Rupicola rupicola]