What is the X in X-mas?
fem. proper name, mid-12c., from Old French Agnes, from Greek Hagne "pure, chaste," from fem. of hagnos "holy," from PIE *yag- "to worship, reverence" (see hagiology). St. Agnes, martyred 303 C.E., is patron saint of young girls, hence the folk connection of St. Agnes' Eve (Jan. 20-21) with love divinations. In Middle English, frequently phonetically as Annis, Annys. In U.S., among the top 50 names for girls born between 1887 and 1919.