Tiernan is a distinctive boys' name in United States, ranking #1787 in 2009 with 85 recorded births. This places Tiernan in the top 12% of ranked US boys' names for the year. Its actual usage is classified as Rare. The name reached its all-time peak in 2007 with 86 births ranking #1738. Since 1996, the popularity has increased by 400.0%. In 2009, approximately 1 in every 23,333 boys born was named Tiernan. FALLING Recent data shows the name is currently falling.