Is it ensure, insure, or assure?
Old English geornan (Mercian), giernan (West Saxon), giorna (Northumbrian), from Proto-Germanic *gernijanan (cf. Gothic gairnjan "to desire," German begehren "to desire"), from *gernaz (cf. Old High German gern, Old Norse gjarn "desirous," Old English georn "eager, desirous," German gern "gladly, willingly"), from PIE root *gher- "to like, want" (see hortatory). Related: Yearned; yearning.