The authors agree that the surname derives from the Germanic personal name Agi Hardhu, composed of agi ("terror, fear inspired in the enemy") and hardhu ("hard, brave"), and that it belongs to the Lombard onomastic repertoire, in which warrior qualities were exalted by combining elements of fierceness with virtues of strength. Both also agree that the meaning points to the idea of a fearsome and brave warrior.

F. Miranda adds that the surname could equally derive from the Germanic Akhard and its Latinised form Achardus, with the sense of "strong weapon, cutting weapon", that is, "strong warrior". For his part, V. Blunda notes that the consonant change gg > cc is characteristic of the phonetics of southern Italy, which explains the current form of the surname.

As for its distribution, Miranda indicates that the surname has a main core in the area of Naples and another in western Sicily, with a presence in Sicily especially in the areas of Trapani, Palermo, Agrigento, Syracuse and Catania. Blunda, on the other hand, characterises it directly as a Sicilian surname.