Fraire is a rare surname, typical of Piedmont, specifically of the areas of Revello, Envie and Saluzzo in the province of Cuneo, with some presence also in Turin. According to the research of Cognomi Italiani, it is very probably a surname of Occitan origin, since it derives from the Occitan term fraire = "brother", a probable nickname given to the ancestor in an affectionate way, or for having had some relation (of work or of kinship) with a friar.

Other theories consider a Jewish origin of the surname. In the Genealogía de la Familia Frayle it is also read that Frayle comes from the Provençal word fraire, and this in turn from the Latin word frater, meaning "brother"; since both the name Juan and the surname Frayle mean "brother", it is suggested they were taken deliberately by a Jewish convert to go unnoticed.

We can therefore distinguish three variants of the surname: the French, the Spanish and the Italian.

The surname Frairia

According to the research of E. Rossoni, it is a surname typical of Turin. Frairia could derive from a dialectal modification of the name Fraire, an archaic form of the French word frère = fratello = "brother", used also as a name in the forms Frérey or Frairey. It is also possible that it is a dialectal alteration of the name Frederich or Fraidirich.