The Mediolanum name is borne by a number of Gallo-Roman sites in France, such as Mediolanum Santonum (Saintes) and Mediolanum Aulercorum (Évreux) and appears to contain the Celtic element -lan, signifying an enclosure or demarcated territory (source of the Welsh word 'llan', meaning a sanctuary or church). Hence, Mediolanum could signify the central town or sanctuary of a particular Celtic tribe.[6][8]

The origin of the name and of a boar as a symbol of the city are fancifully accounted for in Andrea Alciato's Emblemata (1584), beneath a woodcut of the first raising of the city walls, where a boar is seen lifted from the excavation, and the etymology of Mediolanum given as "half-wool", explained in Latin and in French. The foundation of Milan is credited to two Celtic peoples, the Bituriges and the Aedui, having as their emblems a ram and a boar; therefore "The city's symbol is a wool-bearing boar, an animal of double form, here with sharp bristles, there with sleek wool." Alciato credits Ambrose for his account.

The German name for the city is Mailand, while in the local Western Lombard dialect, the city's name is Milán.