The authors agree that the surname was formed from a medieval personal name of Germanic origin whose second element is gari/gaira ("spear").

E. Rossoni derives it from the medieval name Argerius, documented in the Diplomatic Code of Medieval Lombardy in the year 1020 with Argerius notarius imperatoris, active in Alfianello (Brescia area).

V. Blunda, for the Sicilian variant, derives it from the Germanic compound Ar Gari ("eagle's spear" or "aquiline spear"), formed from ar ("eagle", a reduced form of aran) and gari (a variant of gaira, "spear"). He notes that the eagle was a sacred animal of the Germanic peoples, a symbol of sovereignty and connection with the gods, incorporated as a heraldic element in medieval European culture. He adds that the combination with the warrior's spear reflects the ideal of the military leader inspired by the deities.