The authors agree that the surname was formed from the medieval name of Germanic origin Ardengo or Ardingo (*Harding), linked to the root hard- ("strong, brave").

E. De Felice specifies that the Germanic name is formed from the abbreviated, hypocoristic form of compound personal names whose first element is hardhu- ("strong, brave") —such as Ardemanno or Arduino—, that is Ard-, with the derivational suffix -ing. He notes that it was fairly common in the Late Middle Ages: in 920 an Ardingus, bishop of the emperor Berengar, is mentioned in Farfa, and from the 12th century Ardingus is frequent in Tuscan documents. He adds that the surname is rare and sporadic in the north and in Tuscany.

E. Rossoni documents the name Ardengus in the Diplomatic Code of Medieval Lombardy, in a deed of 1189. He also suggests that it may derive from place names such as Villanova d'Ardenghi (Pavia area) or from a locality Ardengo in the Milan area. He records the transformation into a surname in Pisa in the 13th century with Ardengo degli Ardengi, and in Lucca in the 14th century with the Vicar Pietro degli Ardenghi.

It is considered to be a widespread anthroponymic surname, derived from Harding ("strong stock").