B. Zuanella documents the surname from an old anthroponym, Cernè/Černè, attested in the valleys of the Natisone during the 15th and 16th centuries in localities such as Azzida, Iainich and the Judrio valley. In the 17th century it appears already consolidated as a surname in Antro, Azzida, Montefosca, Montemaggiore, Pegliano and Masarolis, under the forms Cerne, Cerna and Cerno. It derives from the Slovene adjective č(e)rn, meaning "black", with the suffix -è, and originally functioned as a nickname for a child of black hair or dark complexion.

Zuanella also details a chain of derivations: from the form Č(e)rnè arose, through the suffix -ič, the patronymic Cernetič/Cernetig ("son of Černè"), preserved to this day in the comune of Stregna; from this in turn derived the reduced form Černèt/Cernèt, alive in Prossenicco and Montefosca. The form Cerno is maintained in Lusevera, in the Torre valleys. From the same Slovene adjective also come the surnames Cernotta, Cernoia and Cernigoi.

E. De Felice agrees in noting the Slovene adjective crn —pronounced with a vocalic r and equivalent to "black, dark"— as the etymological base, and indicates that, more rarely, the Croatian term crn or crnac can also intervene. He notes that the surname is the functional equivalent of the Italian surnames Néri, Négri or Di Négro. De Felice places its diffusion in Friuli-Venezia Giulia, where the base form Cerne is especially frequent in Trieste.