Unknown is a distinctive girls' name in United States, ranking #2334 in 2009 with 84 recorded births. The name reached its all-time peak in 2009 with 84 births ranking #2334. Since 1996, the popularity has increased by 58.5%. In 2009, approximately 1 in every 21,868 girls born was named Unknown. STABLE Recent data shows the name is currently stable.