Ildefonso is a distinctive boys' name in United States, ranking #9023 in 2003 with 7 recorded births. This places Ildefonso in the bottom 29% of ranked US boys' names for the year. Its actual usage is classified as Rare. The name reached its all-time peak in 1997 with 10 births ranking #5811. In 2003, approximately 1 in every 282,181 boys born was named Ildefonso. STABLE Recent data shows the name is currently stable.