backhander

noun
RareNot in standard dictionaries
1

A glass of wine given out of turn, the bottle having been handed backwards.

2

A blow with the back of the hand.

3

A bribe, a secret payment.

4

A shot played backhand, a backhand stroke.

5

A player who plays a backhand shot.

6

A surfer who approaches a swell with the wave behind them ("on their backhand") rather than facing the wave ("on their forehand").

#informal