nanny

From nan (“grandmother; nursemaid”) + -y. The root is from nana (“grandma; nanny”), which is from nanna (“grandmother”), which is possibly derived from Proto-Celtic *nana (“grandmother”). See also Proto-Brythonic *nanī, Welsh nain (“grandmother”), Galician nana (“mama”), Spanish nana (“granny; nanny; mommy; housekeeper”), Sicilian nanna (“grandma”), Italian nonna (“granny”), Late Latin nonna (“nun; tutoress; old woman”), Norman nonne (“nun”), Old French nonain (“nun”). All probably ultimately from a Proto-Indo-European root imitative of a child babbling, similar to Ancient Greek νάννα (nánna).

出典: Wiktionary「nanny」（CC BY-SA 4.0）