Unknown is a distinctive girls' name in United States, ranking #2414 in 2011 with 77 recorded births. The name reached its all-time peak in 2009 with 84 births ranking #2334. Since 1996, the popularity has increased by 45.3%. In 2011, approximately 1 in every 22,842 girls born was named Unknown. STABLE Recent data shows the name is currently stable.