Refund
late Middle English (in the senses ‘pour back’ and ‘restore’): from Old French refonder or Latin refundere, from re- ‘back’ + fundere ‘pour’, later associated with the verb fund. The noun dates from the mid 19th century.
wiktionary
From Middle English refunden, refounden, from Old French refondre, refonder, refunder(“to restore; pay back”), from Latin refundere; prefix re-(“re-”) + fundere(“to pour”): compare French refondre, refonder. See fuse(“to melt”), and compare refound(“to cast again”), and refuse.
etymonline
refund (v.)
early 15c., refounden, refunden, "to pass on, transmit;" also "to return" (earlier "to pour back," late 14c.); from Old French refunder, refounder, refondre "restore" and directly from Latin refundere "give back, restore, return," literally "pour back, flow back," from re- "back" (see re-) + fundere "to pour" (from nasalized form of PIE root *gheu- "to pour").
Century Dictionary speculates that Old French refounder in the sense "restore" was confused with refonder, refunder, "re-establish, rebuild, restore ("refound"). In some senses also influenced by fund (n.). Specifically as "to resupply with money" from 1550s. Related: Refunded; refunding.
refund (n.)
"a repayment, return of money paid," 1782, from refund (v.).
