Tiernan is a distinctive boys' name in United States, ranking #4319 in 2019 with 24 recorded births. The name reached its all-time peak in 2007 with 86 births ranking #1738. Since 1996, the popularity has increased by 41.2%. In 2019, approximately 1 in every 74,723 boys born was named Tiernan. FALLING Recent data shows the name is currently falling.