Source : Webster's Revised Unabridged Dictionary (1913)

Racer \Ra"cer\, n.
   1. One who, or that which, races, or contends in a race;
      esp., a race horse.

            And bade the nimblest racer seize the prize. --Pope.

   2. (Zo["o]l.) The common American black snake.

   3. (Mil.) One of the circular iron or steel rails on which
      the chassis of a heavy gun is turned.

Source : WordNet®

racer
     n 1: someone who drives racing cars at high speeds [syn: {race
          driver}, {automobile driver}]
     2: a fast car that competes in races [syn: {race car}, {racing
        car}]
     3: an animal that races
     4: slender fast-moving North American snakes