​MOUSTACHE, or Mustachio, the hair worn unshaven on the upper lip (see Beard). The spelling “moustache,” now the most common in English usage, is the French form of Ital. mustachio, an adaptation of a Doric dialectical μύσταξ, upper lip, also hair on the lip; this is generally taken to be a variant of μάσταξ, jaws, mouth, connected with μάσασθαι, to chew; cf. “mastic,” chewing-gum, and “masticate,” to chew.