ringer

Etymology 1

From Middle English ringere, rynger, ryngar, equivalent to ring (“to sound a bell”) + -er.

noun

1. Someone who rings, especially a bell ringer.
   Pull, if ye never pull′d before; Good ringers, pull your best," quoth he. 1863, Jean Ingelow, High Tide on the Coast of Lincolnshire
2. (mining) A crowbar.

Etymology 2

From ring (“to surround”) + -er.

noun

1. (games) In the game of horseshoes, the event of the horseshoe landing around the pole.
2. (uncountable, games) A game of marbles where players attempt to knock each other's marbles out of a ring drawn on the ground.
3. A ringer T-shirt.
   […] shabby baseball caps, faded and worn-out T-shirts, ringers and polos with artificially aged hems […] 2007, Descant, number 138, page 28
   The shirts were light blue heather ringers with royal blue trim on the necks and sleeves. 2011, Buck Peden, Baseball, Golf, Wars, Women & Puppies: An Autobiography, page 278

Etymology 3

Probably from ring the changes.

noun

1. (sports) A person highly proficient at a skill or sport who is brought in, often fraudulently, to supplement a team.
2. (horse racing) A horse fraudulently entered in a race using the name of another horse.
3. A person, animal, or entity which resembles another so closely as to be taken for the other, now usually in the phrase dead ringer.
   I mean, he knows we never handed off the briefcase, but he never asked for it back. The million bucks was never in the briefcase! The asshole was hoping that they would kill her! You threw out a ringer for a ringer! 1998, Ethan Coen, Joel Coen, The Big Lebowski (motion picture), spoken by The Dude (Jeff Bridges)
4. (UK, slang) A fraudulently cloned motor vehicle.
   I had heard early on in my career about 'ringers': cars that were stolen and cloned, but it was 1993 before I was to experience this first-hand. 2020, Tom Hartley, Tom Hartley: The Dealmaker

Etymology 4

Unknown. Probably so named after the custom of ringing a bell to denote the winner of a contest or competition.

noun

1. (UK, dialect) A top performer.
2. (Australia) The champion shearer of a shearing shed.
   Click goes his shears; click, click, click. Wide are the blows, and his hand is moving quick, The ringer looks round, for he lost it by a blow, And he curses that old shearer with the bare belled ewe. 5 Dec 1891, The Bacchus Marsh Express, Victoria, page 7, column 7
3. (Australia) A stockman, a cowboy.
   1964, Alec Bolton, Walkabout′s Australia, Walkabout magazine, page 107, The ringers are the stockmen on a station. The cattle pass through their hands before the drovers lift them and take them along the stock routes that lead to the killing pens in cities.
   This vast holding is run by six ringers and six boys. A ringer is a qualified stationhand and a boy is a trainee. It takes four years for a boy to become a ringer. 1987, Geoffrey Atkinson, Philip Quirk., The Australian Adventure: The Explorer′s Guide to the Island Continent, page 175
   Most people associated with the Australian beef industry believe the ringer′s skill of throwing cattle by the tail to be a practice that is purely Australian. There is ample evidence however, that it was practised in South and Central America long before it was developed here. 2005, Jake Drake, The Wild West in Australia and America, page 156

Etymology 5

Perhaps dissimilated from Middle English wringere (“stingy person, pennypincher, one who financially oppresses, an extortioner”).

noun

1. (slang) Any person or thing that is fraudulent; a fake or impostor.
2. (slang) A look-alike.
   That man over there is an exact ringer for my father!

Etymology 6

ring + -er, from the noun.

noun

1. (UK, military, informal, in combination) An officer having the specified number of rings (denoting rank) on the uniform sleeve.
   A group of naval one- and two-ringers were chatting by the office door with a few ratings, complete with kit-bags and oilskins. 2012, John Harris, The Lonely Voyage
   The senior officer of the escort was an RN two and a half ringer who had a reputation of being one of the best. 2013, Dudley Pope, Convoy