Unknown is a distinctive girls' name in United States, ranking #3647 in 2015 with 43 recorded births. The name reached its all-time peak in 2009 with 84 births ranking #2334. Since 1996, the popularity has decreased by 18.9%. In 2015, approximately 1 in every 41,504 girls born was named Unknown. STABLE Recent data shows the name is currently stable.