Unknown is a distinctive girls' name in United States, ranking #5251 in 2005 with 25 recorded births. The name reached its all-time peak in 2009 with 84 births ranking #2334. Since 1996, the popularity has decreased by 52.8%. In 2005, approximately 1 in every 73,908 girls born was named Unknown. STABLE Recent data shows the name is currently stable.