Unknown is a distinctive girls' name in United States, ranking #4802 in 2007 with 31 recorded births. The name reached its all-time peak in 2009 with 84 births ranking #2334. Since 1996, the popularity has decreased by 41.5%. In 2007, approximately 1 in every 62,014 girls born was named Unknown. STABLE Recent data shows the name is currently stable.