ringer

UK: ˈrɪŋə | US: ˈrɪŋər

Definition
  1. n. 1. A person or thing that rings (e.g., a bell ringer).

  2. n. 2. A duplicate or substitute, especially one fraudulently passed off as genuine (e.g., a horse ringer in a race).

  3. n. 3. (Slang) A highly skilled or outstanding person in a field (e.g., "He's a ringer at chess").

Structure
ring <to sound a bell>er <agent noun suffix>
Etymology

The word "ringer" originates from the verb "ring," which traces back to Old English hringan, meaning "to sound a bell." The suffix "-er" is an agentive suffix in English, used to denote someone or something performing an action (e.g., "singer," "writer"). Over time, "ringer" evolved metaphorically to describe a fraudulent substitute (sense 2), likely from the idea of "ringing in" a fake, and later slang extended it to mean an exceptional person (sense 3).

Examples
  1. The church ringer tolled the bell at noon.

  2. The racehorse was a ringer, secretly replaced to ensure victory.

  3. She’s a real ringer when it comes to solving puzzles.

  4. The team brought in a ringer for the championship game.

  5. The antique vase turned out to be a ringer—a clever imitation.