Is it ensure, insure, or assure?
early 15c., "occur as a result, arise as a consequence," from Medieval Latin resultare "to result," in classical Latin "to spring forward, rebound," frequentative of past participle of resilire "to rebound" (see resilience). Related: Resulted; resulting.
1620s, "action of springing back;" 1640s, "outcome, effect," from result (v.). Related: Results. Mathematical sense from 1771.