According to E. De Felice, Acerbi is an old northern Italian surname, particularly associated with Lombardy and the Milan area. It derives from the nickname or personal name Acèrbo, based on the Italian adjective acerbo, from the Latin acerbus. In medieval usage, the term could describe someone who was harsh, severe, stern, or uncompromising in character.

Both E. De Felice and E. Rossoni note a second possible interpretation linked to the meaning of acerbo as “immature,” “premature,” or “not yet fully developed.” In this sense, the name may have originally referred to a child born prematurely, a very young family member, or someone considered youthful or inexperienced.

E. Rossoni agrees with this dual interpretation, emphasizing that the surname may have originated either as a nickname describing an ancestor’s temperament or as a reference to circumstances surrounding birth, age, or maturity. The surname belongs to a broader group that includes regional variants such as Acerbis, Acerboni, and Acerbo.

Ultimately, Acerbi derives from a medieval nickname or personal name rooted in the Latin acerbus, carrying meanings ranging from “harsh” or “severe” to “premature” or “immature,” depending on the original context in which it was bestowed.