The Collaborative International Dictionary of English v.0.48:

Pike \Pike\, n. [F. pique; perhaps of Celtic origin; cf. W. pig
   a prick, a point, beak, Arm. pik pick. But cf. also L. picus
   woodpecker (see Pie magpie), and E. spike. Cf. Pick, n. &
   v., Peak, Pique.]
   1. (Mil.) A foot soldier's weapon, consisting of a long
      wooden shaft or staff, with a pointed steel head. It is
      now superseded by the bayonet.
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   2. A pointed head or spike; esp., one in the center of a
      shield or target. --Beau. & Fl.
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   3. A hayfork. [Obs. or Prov. Eng.] --Tusser.
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   4. A pick. [Prov. Eng.] --Wright. Raymond.
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   5. A pointed or peaked hill. [R.]
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   6. A large haycock. [Prov. Eng.] --Halliwell.
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   7. A turnpike; a toll bar. --Dickens.
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   8. (Zool.) sing. & pl. A large fresh-water fish (Esox
      lucius), found in Europe and America, highly valued as a
      food fish; -- called also pickerel, gedd, luce, and
      jack.
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   Note: Blue pike, grass pike, green pike, wall-eyed pike, and
         yellow pike, are names, not of true pike, but of the
         wall-eye. See Wall-eye.
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   Gar pike. See under Gar.

   Pike perch (Zool.), any fresh-water fish of the genus
      Stizostedion (formerly Lucioperca). See Wall-eye,
      and Sauger.

   Pike pole, a long pole with a pike in one end, used in
      directing floating logs.

   Pike whale (Zool.), a finback whale of the North Atlantic
      (Bal[ae]noptera rostrata), having an elongated snout; --
      called also piked whale.

   Sand pike (Zool.), the lizard fish.

   Sea pike (Zool.), the garfish
      (a) .
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WordNet (r) 3.0 (2006):

Esox lucius
    n 1: voracious piscivorous pike of waters of northern hemisphere
         [syn: northern pike, Esox lucius]