Is it ensure, insure, or assure?
c.1200, "bountiful, inclined to give or spend freely," also, of areas, "great in expanse," from Old French large "broad, wide; generous, bounteous," from Latin largus "abundant, copious, plentiful; bountiful, liberal in giving," of unknown origin. Main modern meanings "extensive; big in overall size" emerged 14c. An older sense of "liberated, free from restraining influence" is preserved in at large (late 14c.). Adjective phrase larger-than-life first attested 1937 (bigger than life is from 1640s).