The Collaborative International Dictionary of English v.0.48:

Striker \Strik"er\, n.
   1. One who, or that which, strikes; specifically, a
      blacksmith's helper who wields the sledge.
      [1913 Webster]

   2. A harpoon; also, a harpooner.
      [1913 Webster]

            Wherever we come to an anchor, we always send out
            our strikers, and put out hooks and lines overboard,
            to try fish.                          --Dampier.
      [1913 Webster]

   3. A wencher; a lewd man. [Obs.] --Massinger.
      [1913 Webster]

   4. A workman who is on a strike.
      [1913 Webster]

   5. A blackmailer in politics; also, one whose political
      influence can be bought. [Political Cant]
      [1913 Webster]

WordNet (r) 3.0 (2006):

striker
    n 1: a forward on a soccer team
    2: someone receiving intensive training for a naval technical
       rating
    3: an employee on strike against an employer
    4: someone who hits; "a hard hitter"; "a fine striker of the
       ball"; "blacksmiths are good hitters" [syn: hitter,
       striker]
    5: the part of a mechanical device that strikes something