rewarder

noun

1. something given in return for good or, sometimes, evil, or for service or merit
2. money offered, as for the capture of a criminal, the return of something lost, etc.
3. compensation; profit
4. Psychol. a return for correct response to a stimulus

Origin: ME < NormFr, for OFr regarde

transitive verb

1. to give a reward to
2. to give a reward for
3. to serve as a reward to or for

Origin: ME rewarden < NormFr rewarder, for OFr regarder: see regard