What does Guillaume mean?
Guillaume \gu(i)-llau-me\ as a boys' 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 has 31 more alternative forms via William: Bill▼, Bille, Billie▼, Billy▼, 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.
Guillaume is a rare given name for men but a very popular last name for both adults and children (#15813 out of 88799, Top 18%). (2000 U.S. Census)
Below is a graphed analysis of the usage of Guillaume and corresponding names. 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 popular alternative forms of Guillaume (#unlisted). Usage of this boy name reached its peak during 1920-1929 and is now much lower, with versions such as Billy, Guillermo, Will, Willie and Wilson falling out of fashion. Liam (#2) is the most trendy boy name in this list. (Top 1000 Baby Names Records, 2014)