Non-Runner No Bet (often shortened to NRNB) is a term used in various sports but is most commonly used in the sport of horse racing. It describes the terms of a bet. If the selection doesn't run in a race and the bet is under the condition of non-runner no bet, then the stake is returned to the customer.

nonrunner in British English\n\n (nRnrnY ) noun. a person who does not run regularly or train in the manner of an athlete or professional runner.