What is the X in X-mas?
mid-14c., "a regarding, heeding, observation," from Anglo-French and Old North French reward, back-formation from rewarder (see reward (v.)). Meaning "repayment for some service" is from late 14c. Sense of "sum of money in exchange for capture" is from 1590s.
c.1300 "to grant, bestow;" early 14c. "to give as compensation," from Old North French rewarder "to regard, reward," variant of Old French regarder "take notice of, regard, watch over," from re-, intensive prefix (see re-), + garder "look, heed, watch" (see guard (v.)). Originally any form of requital. A doublet of regard. Related: Rewarded; rewarding.
reward re·ward (rĭ-wôrd')
The return for the performance of a behavior that is desired; a positive reinforcement.