E. De Felice: widespread in the North, and more frequent in Emilia-Romagna and in Lombardy (respectively for the forms in -r- and in -l-). It may have several etymologies and various interpretations, which today can hardly be identified and distinguished. The most likely hypotheses are: the formation from acciàio ("steel") in the northern forms azaro and azàr (see Acciài) and in some cases from acciarino; the derivation from azza, aza "axe" or also "azza", as a bladed weapon of medieval and Renaissance war; the derivation from the name Azzo (see Azzi).

E. Rossoni: the origin is probably a trade name derived from the term azzar ("steel"), designating those who worked or produced steel. A derivation from the term aza ("axe") is also possible, referring to those who used or made axes.