1 a esp. US an athlete or horse entered in a competition by fraudulent means, esp. as a substitute. b a person's double, esp. an imposter.
2 Austral. a the fastest shearer in a shed. b a stockman or station hand.
3 a person who rings, esp. a bell-ringer.
Phrases and idioms:
be a ringer (or dead ringer) for resemble (a person) exactly.
Etymology: RING(2) + -ER(1)
Useful english dictionary. 2012.