Guillaume is a distinctive boys' name in United States, ranking #6363 in 2005 with 12 recorded births. The name reached its all-time peak in 1997 with 19 births ranking #3648. Since 1996, the popularity has decreased by 25.0%. In 2005, approximately 1 in every 166,429 boys born was named Guillaume. FALLING Recent data shows the name is currently falling.