Source : Webster's Revised Unabridged Dictionary (1913)

Ringer \Ring"er\, n.
   1. One who, or that which, rings; especially, one who rings
      chimes on bells.

   2. (Mining) A crowbar. --Simmonds.

Ringer \Ring"er\, n. (Horse Racing)
   A horse that is not entitled to take part in a race, but is
   fraudulently got into it.

Source : WordNet®

ringer
     n 1: a person who rings church bells (as for summoning the
          congregation) [syn: {toller}, {bell ringer}]
     2: a person who is almost identical to another [syn: {dead
        ringer}, {clone}]
     3: a contestant entered in a competition under false pretenses
     4: (horseshoes) the successful throw of a horseshoe or quoit so
        as to encircle a stake or peg