E. De Felice notes that this surname was formed from the appellative and nickname Frate, derived from frate —and in Venetan frare—, with the meanings of "friar" and "brother", including its altered forms. Its distribution in Italy is sporadic, with the variant Frare peculiar to the Veneto and compound forms documented in southern Italy.

V. Blunda offers a perspective centred on Sicily: the surname would have a dialectal origin, derived from the Sicilian word fràti, with the specific sense of "brother" in the sphere of blood kinship, without ecclesiastical connotation. Although in standard Italian frati is the plural of "friar", the motivation of the Sicilian surname refers to the blood bond within the traditional extended family.

Both authors agree that the etymological base is the same word —frate / frati—, but they differ in the emphasis: De Felice contemplates both the religious and the fraternal meaning in a broader context, while Blunda restricts the interpretation to the specifically Sicilian dialectal use.