Tiernan is a distinctive boys' name in England & Wales, ranking #1407 in 2023 with 18 recorded births. The name reached its all-time peak in 1999 with 24 births ranking #697. Since 1996, the popularity has increased by 80.0%. In 2023, approximately 1 in every 15,370 boys born was named Tiernan. FALLING Recent data shows the name is currently falling.