Merriam-Webster's Collegiate® Dictionary, 11th Edition
REFUND
I. transitive verb see: found
Date: 15th century
to give or put back, to return (money) in restitution, repayment, or balancing of accounts, refundability noun refundable adjective
II. noun
Date: 1866
the act of refunding, a sum refunded,
III. transitive verb
Etymology: re- + 2fund
Date: circa 1860
to fund again