The authors agree that it is a surname of Friulian origin, derived from the place name Forgaria —in Friulian Folgjària—, a locality of central Friuli near Osoppo (today Forgaria nel Friuli, in the province of Udine). Both also agree that the epicentre of its distribution is Gemona, with notable presence in Osoppo and Udine.

E. Costantini provides the oldest documentation in Gemona: Simonut forgarino in 1571 and Forgerins in 1575. He also notes that the surname probably formed autonomously in Gemona and in Osoppo, where a domeni vidon forgarino appears in 1595. He likewise records presence in Tolmezzo.

E. De Stefani goes deeper into the etymology of the base place name, connecting it with the Latin fulgur ("lightning") plus the suffix -ariu, so that it would designate a place "struck by lightning"; he notes a parallel in the Middle French fouldriere. He warns that it should not be confused with the place name Folgaria of the province of Trento, which derives from the Latin filicaria ("place of ferns").