What does Willem mean?
Willem has 33 different forms via William: Bill▼, Bille, Billie▼, Billy▼, Guglielmo, Guillaume, Guillermo▼, Liam, Vilhelm, Villem, Wilek, Wiley▼, Wilhelm▼, Wilhelmus, Wilkes, Wilkie, Wilkinson, Will▼, Willhelmus, Willi, Williams▼, Williamson, Willie▼, Willis▼, Willkie, Wills, Willson, Willy, Wilmer▼, Wilmot, Wilmott, Wilson▼ and Wim.
Willem is an uncommon given name for males but a very popular last name for all people (#70906 out of 150436, Top 47%). (2000 U.S. Census)
Shown below is an analysis of the usage of Willem and related names. Bill, Billie, Billy (#794 the previous year), Guillermo (#678), Liam (#2), Wiley, Wilhelm, Will (#763), William (#5), Williams, Willie (#722), Willis, Willy, Wilmer and Wilson (#594) are the popular variation forms of Willem (#unlisted) appearing in the Top 1000. Usage of these boy names was at its most widespread during the years 1920-1929 (usage of 0.5873%) and is now much lower (usage 0.2295%, down 60.9%), with forms like Billy, Guillermo, Will, Willie and Wilson becoming somewhat dated. Liam (#2) is the most trendy baby name here. (2014 Birth Statistics)