Is it ensure, insure, or assure?
c.1200, "sum paid for the release of a prisoner or captured man," from Old French ranson (Modern French rançon), earlier raenson "ransom, redemption," from Latin redemptionem (nominative redemptio) "a redeeming," from redimere (see redeem).
early 14c., from ransom (n.). Related: Ransomed; ransoming.
the price or payment made for our redemption, as when it is said that the Son of man "gave his life a ransom for many" (Matt. 20:28; comp. Acts 20:28; Rom. 3:23, 24; 1 Cor. 6:19, 20; Gal. 3:13; 4:4, 5: Eph. 1:7; Col. 1:14; 1 Tim. 2:6; Titus 2:14; 1 Pet. 1:18, 19. In all these passages the same idea is expressed). This word is derived from the Fr. rancon; Lat. redemptio. The debt is represented not as cancelled but as fully paid. The slave or captive is not liberated by a mere gratuitous favour, but a ransom price has been paid, in consideration of which he is set free. The original owner receives back his alienated and lost possession because he has bought it back "with a price." This price or ransom (Gr. lutron) is always said to be Christ, his blood, his death. He secures our redemption by the payment of a ransom. (See REDEMPTION.)