Source : Webster's Revised Unabridged Dictionary (1913)

Wrecker \Wreck"er\, n.
   1. One who causes a wreck, as by false lights, and the like.

   2. One who searches fro, or works upon, the wrecks of
      vessels, etc. Specifically:
      (a) One who visits a wreck for the purpose of plunder.
      (b) One who is employed in saving property or lives from a
          wrecked vessel, or in saving the vessel; as, the
          wreckers of Key West.

   3. A vessel employed by wreckers.

Source : WordNet®

wrecker
     n 1: someone who demolishes or dismantles buildings as a job
     2: someone who commits sabotage or deliberately causes wrecks
        [syn: {saboteur}, {diversionist}]
     3: a truck equipped to hoist and pull wrecked cars (or to
        remove cars from no-parking zones) [syn: {tow truck}, {tow
        car}]