Derived from the personal name Alfonso, Alfonsi is a patronymic surname meaning “son of Alfonso.”

The name Alfonso has Germanic origins and is generally traced to the ancient name Adalfuns (or Athalafuns), composed of elements meaning “noble” and “ready,” “willing,” or “eager.” Over time, the name spread throughout medieval Europe and became particularly popular in the Iberian Peninsula and Italy.

As a surname, Alfonsi originally identified the descendants of a man named Alfonso. Its meaning is therefore commonly interpreted as “descendant of Alfonso,” a name traditionally associated with nobility, courage, and leadership.