Meaning and name origin
Guillaume \gu(i)-llau-me\ as a boy's name is pronounced gee-OHM. It is of Old German origin, and the meaning of Guillaume is "determined protector". French variant of William. Guillermo (gui-YARE-mo) is a Latin form. French poet Guillaume Apollinaire.
Guillaume is not a popular first name for males but a very popular surname or last name for all people (#15813 out of 88799, Top 18%) (2000 U.S. Census).
Displayed below is a comparison of the popularity of the boy name Guillaume and its variant forms. Popular variation forms ranked in the Top 1000/100 are William (#5) and Guillermo (#678). (2014 statistics).