Unknown is a distinctive girls' name in United States, ranking #3267 in 2000 with 42 recorded births. The name reached its all-time peak in 2009 with 84 births ranking #2334. Since 1996, the popularity has decreased by 20.8%. In 2000, approximately 1 in every 43,237 girls born was named Unknown. STABLE Recent data shows the name is currently stable.