Tiernan is a distinctive boys' name in United States, ranking #3570 in 2021 with 32 recorded births. The name reached its all-time peak in 2007 with 86 births ranking #1738. Since 1996, the popularity has increased by 88.2%. In 2021, approximately 1 in every 54,632 boys born was named Tiernan. FALLING Recent data shows the name is currently falling.