What does Guillermo mean?
Guillermo /guil-ler-mo/ as a name for boys. Guillermo's name origin is Old German, and the name Guillermo means "determined protector". Guillermo is a Spanish form of Guillaume (Old German): French variation of William. Compare surname Glerum.
How popular is Guillermo?
Guillermo is a very prominent first name for men (#379 out of 1220, Top 31%) and also a very prominent last name for both adults and children (#11647 out of 150436, Top 8%). (2000 U.S. Census)
Displayed below is the birth name popularity of Guillermo for boys. Guillermo was first listed in 1900-1909 and reached its apex rank of #352 in the U.S. in the year 1996, and is at #678 currently. (Top 1000 Birth Names Statistics, 2014)
The only other popular variation form of Guillermo (#678 in 2014) is William (#5 in 2014). Adoption of these forms of Guillermo was widespread among parents in 1996 (usage of 0.82%) and is now significantly lower (usage 0.66%, 19% less). Displayed below is a comparison of the popularity of Guillermo and related names. (Top 1000 Birth Names Statistics, 2014)