Meaning and name origin
Guglielmo \g(u)-gliel-mo, gug-lie-lmo\ as a boy's name is of Old German origin, and the meaning of Guglielmo is "determined protector". Guglielmo is a variant of Guillaume (Old German): French variant of William.
Guglielmo is not a popular first name for males but a very popular surname or last name for all people (#13051 out of 88799, Top 15%) (2000 U.S. Census).
Displayed below is a comparison of the popularity of the boy name Guglielmo and its source forms. The only popular variation form ranked in the Top 1000/100 is William (#5). (2014 statistics).