What does Guglielmo mean?
Guglielmo \g(u)-gliel-mo, gug-lie-lmo\ as a boys' name is of Old German derivation, and the name Guglielmo means "determined protector". Guglielmo is a derivative of Guillaume (Old German): French variant of William.
Guglielmo has 36 alternative forms via Guillaume, William: Bill▼, Bille, Billie▼, Billy▼, Gillermo, Guilherme, Guillermo▼, Gwillyn, Gwilym, Liam, Vilhelm, Villem, Wilek, Wiley▼, Wilhelm▼, Wilhelmus, Wilkes, Wilkie, Wilkinson, Will▼, Willem, Willhelmus, Willi, Williams▼, Williamson, Willie▼, Willis▼, Willkie, Wills, Willson, Willy, Wilmer▼, Wilmot, Wilmott, Wilson▼ and Wim.
Guglielmo is an uncommon first name for men but a very popular surname for both adults and children (#13820 out of 150436, Top 9%). (2000 U.S. Census)
Bill, Billie, Billy (#794 in 2014), Guillermo (#678), Liam (#2), Wiley, Wilhelm, Will (#763), William (#5), Williams, Willie (#722), Willis, Willy, Wilmer and Wilson (#594) are the prominent related forms of Guglielmo (#unlisted) listed in the Top 1000. These boy names were at the peak of their popularity during the years 1920-1929 (usage of 0.5873%) and have become much less popular since (usage 0.2295%, down 60.9%), with forms such as Billy, Guillermo, Will, Willie and Wilson becoming somewhat dated. Liam (#2) is the most contemporarily stylish birth name here. Below is a graphed comparison of the usage of the boy name Guglielmo and affiliated names. (2014 Birth Statistics)