Meaning

noun your grandmother

noun the mother of your father or mother

noun a river of western Thailand flowing southward to join the Ping River to form the Chao Phraya

originFrom Nan, pet form of the formerly very common female given names Anne and Agnes. As a nursemaid and grandmother, a clipping of earlier nana, from nanny under the probable influence of mama, also from Nan. Compare Mary.

Etymology from Wiktionary, CC BY-SA 3.0