Iain is a distinctive boys' name in United States, ranking #1491 in 1998 with 74 recorded births. The name reached its all-time peak in 2003 with 126 births ranking #1181. Since 1996, the popularity has decreased by 14.0%. In 1998, approximately 1 in every 25,829 boys born was named Iain. FALLING Recent data shows the name is currently falling.