ringer

from The Century Dictionary.

• noun In quoits, a throw by which the quoit is cast so as to encircle the pin.
• noun One who rings; specifically, a bell-ringer.
• noun Any apparatus for ringing chimes, or a bell of any kind.
• noun In mining, a crowbar.
• noun In athletics, one who competes in some way under deception, concealing his identity, ability, or standing.
• noun In racing, a horse entered in a race with intent to deceive.
• noun In sheep-shearing, one who rings or tops the score. See ring.
• noun In general, one who excels others, as if able to run rings around his competitors and still keep ahead. See ring.
• noun A supplementary enthusiastic cheer.
• noun In telephony, an electric call-ben.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Horse Racing) A horse that is not entitled to take part in a race, but is fraudulently got into it.
• noun One who, or that which, rings; especially, one who rings chimes on bells.
• noun (Mining) A crowbar.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Someone who rings, especially a bell ringer.
• noun games In the game of horseshoes, the event of the horseshoe landing around the pole.
• noun uncountable, games A game of marbles where players attempt to knock each other's marbles out of a ring drawn on the ground.
• noun horse racing A horse fraudently entered in a race using the name of another horse.
• noun sports A person highly proficient at a skill or sport who is brought in, often fraudulently, to supplement a team.
• noun A person, animal, or entity which resembles another so closely as to be taken for the other; now usually in the phrase dead ringer.
• noun UK, dialect A top performer.
• noun Australia The champion shearer of a shearing shed.
• noun Australia A stockman, a cowboy.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun (horseshoes) the successful throw of a horseshoe or quoit so as to encircle a stake or peg
• noun a person who rings church bells (as for summoning the congregation)
• noun a person who is almost identical to another
• noun a contestant entered in a competition under false pretenses