Unknown is a distinctive girls' name in United States, ranking #2749 in 2010 with 65 recorded births. The name reached its all-time peak in 2009 with 84 births ranking #2334. Since 1996, the popularity has increased by 22.6%. In 2010, approximately 1 in every 27,343 girls born was named Unknown. STABLE Recent data shows the name is currently stable.