payback (n.)

c. 1200, paien, "to appease, pacify, satisfy, be to the liking of," from Old French paier "to pay, pay up" (12c., Modern French payer), from Latin pacare "to please, pacify, satisfy" (in Medieval Latin especially "satisfy a creditor"), literally "make peaceful," from pax (genitive pacis) "peace" (see peace).

The meaning "to give what is due for goods or services" arose in Medieval Latin and was attested in English by early 13c.; the sense of "please, pacify" died out in English by 1500. Figurative sense of "suffer, endure" (a punishment, etc.) is first recorded late 14c. Meaning "to give or render" with little or no sense of obligation (pay attention, pay respects, pay a compliment) is by 1580s. Meaning "be remunerative, be profitable, yield a suitable return or reward" is by 1812. Related: Paid; paying. To pay up was originally (mid-15c.) "make up the difference between two sums of money;" the sense of "pay fully or promptly" is by 1911. Pay television is attested by 1957.

"being behind, away from the front, in a backward direction," Middle English, from back (n.) and back (adv.); it is often difficult to distinguish from these when the word is used in combinations. Formerly with comparative backer (c. 1400), also backermore. To be on the back burner in the figurative sense of "postponed" is by 1960, from the image of a cook keeping a pot there to simmer while at work on another concoction at the front of the stove.