The authors agree that the surname derives from a personal name of Germanic origin, formed by the elements magin- ("strength, power") and harja- ("army, host"), with the approximate meaning of "powerful army" or "strength of the army".

E. De Felice documents the Latinized form Mainerius as a surname as early as 1363 in Turin, and reconstructs the Germanic etymon of Frankish tradition as *Maginharius. He notes a presence of the surname in north-western Italy, as well as a related variant, Manieri, in the Salento area —that is, the southernmost zone of the region of Puglia, in southern Italy.

V. Blunda approaches the surname from the Sicilian perspective and broadens the cultural context: in ancient Germanic military organization, the collective strength of the army was conceived as the sum of the individual strengths of each warrior, a principle that structured the hierarchy of the contingents contributed by each lineage in the service of the king.