バック

Etymology 1
From.

Noun

 * 1) back
 * 2) a backer, a supporter someone who supports a person or enterprise
 * 3) reversing, moving backwards
 * 4)  additional income on top of basic pay, derived from things like one's clients purchasing alcohol
 * 5)  a back a position (player) behind most others on the team
 * 6)  backhand
 * 7)  the backstroke
 * 1)  backhand
 * 2)  the backstroke
 * 1)  the backstroke

Verb

 * 1) go back
 * 2) move backwards
 * 3) give a refund
 * 1) give a refund