Is it ensure, insure, or assure?
early 15c., "to prolong, extend," from Old French proroger, proroguer (14c.), from Latin prorogare, literally "to ask publicly," from pro "before" (see pro-) + rogare "to ask" (see rogation). Perhaps the original sense in Latin was "to ask for public assent to extending someone's term in office." Legislative meaning "discontinue temporarily" is attested from mid-15c. Related: Prorogation.