The authors agree that the surname derives from the Germanic brun, meaning "dark" or "brown", which originally designated people with dark hair or complexion. This nickname gave rise to the given name Bruno, from which in turn arose surnames such as Brunetta, Brunetti and Brunetto. The ending -etta reflects the Latin suffix -itta(m), of diminutive value.

E. De Stefani notes that Brunetta is frequent in the Trieste area and in localities such as Pordenone, Cordenons, Porcia and Azzano Decimo, with historical presence documented in Tolmezzo from the beginning of the 15th century and in the Carnia —a mountainous area of northern Friuli, in the province of Udine—. He also indicates that in Udine and its surroundings variants such as Brun, Bruna, Brunelli, Brunello, Brunettin, Brunetto and Bruno coexist.

E. Rossoni specifies that Brunetta presents an important cluster between the Pordenone and Treviso areas, and notes another possibly autochthonous one in Carpignano Salentino, in the Lecce area —the Salento area, that is, the southernmost zone of the Puglia region—. Rossoni also highlights that Brunetti is of pan-Italian distribution, and that Brunetto presents clusters in the Turin area, in Villafranca di Verona, in Rialto in the Savona area, and in various points of Sicily. He adds that the most illustrious historical example of the base name is Brunetto Latini, notary and figure of the Guelph party, mentor of Dante Alighieri and cited in the Inferno.