refund (v.) Look up refund at Dictionary.com
"to give back, restore," early 15c. (earlier "to pour back," late 14c.), from O.Fr. refunder "restore," from L. refundere "give back, restore," lit. "pour back," from re- "back" + fundere "to pour" (see found (2)). Specifically of money from 1550s. The noun is 1866, from the verb.