Is it ensure, insure, or assure?
late 15c., from Old French maternel (14c.), from Vulgar Latin *maternalis, from Latin maternus "maternal, of a mother," from mater "mother" (see mother (n.1)).
maternal ma·ter·nal (mə-tûr'nəl)adj.
Relating to or characteristic of a mother.
Inherited from one's mother.