For B. Zuanella it is a surname derived from the hagionym Vitus (Saint Vitus), through the German form Veit (pronounced Fajt), which in Slovene mouths became Bajt. It is spread practically throughout Slovenia and is one of the typical surnames of the Judrio valley, from where it emigrated to Cividale and sporadically to the valleys of San Leonardo. According to the parish books of San Pietro al Natisone, the Bait present in Ponteacco and San Pietro is of proven Slovene origin and comes from the Caporetto area, specifically from the hamlet of Ladra on the left bank of the Isonzo. On 30 January 1799 a certain Lorenzo, son of Luca Bait of Ladra, married Joanna Sracar of Mezzana and settled there; his son Michele Bait (born in Mezzana on 27/8/1802) would marry on 10/2/1830 Maria Cedarmas of Ponteacco. From Mezzana the surname then descended to Ponteacco.

According to E. Rossoni, it derives from a dialectal variation of the place name Veit (Saint Vitus), whose pronunciation Fait was modified by Slovene speech into Bait.

A hagionym (from the Greek hágios, "holy", + ónoma, "name") is a technical term of onomastics that designates the proper name of a saint, or a name derived from it. In the context of Italian surnames, hagionyms are surnames formed from the name of a saint, whether directly or through derivations.