E. De Stefani documents that the surname originates at Clauzetto, where it is attested from at least the middle of the 16th century, and that from there it migrated towards Carnia by way of the val Cjampon in the 18th century. Today it is found frequently at Preone, Entrampo —a hamlet of Ovaro— and Tolmezzo, and more sporadically at Socchieve and Prato Carnico, as well as at Vito d'Asio, Pordenone and Udine.

On the etymology, De Stefani proposes as his main hypothesis a connection with the Friulian term meche, which designates a pedantic, hesitant or excessively delicate person, a word related to the Agordino mek, of similar sense. The apparent phonological difficulty between mek and Mecchia is resolved by the strong tendency towards diphthongization proper to the speech of Clauzetto. He rules out as less convincing the connection with the Venetian mechia or mechiato, the name of a kind of fish, for lack of a clear nickname motivation.

E. Rossoni agrees in noting Tolmezzo and Preone as areas where the surname has taken root, but proposes different etymologies: a tool for boring wood called mecchia, a root used as a seasoning in peasant cooking, or else an alteration of a reduced form of the name Domenica.