Unknown is a distinctive girls' name in United States, ranking #6204 in 2004 with 20 recorded births. The name reached its all-time peak in 2009 with 84 births ranking #2334. Since 1996, the popularity has decreased by 62.3%. In 2004, approximately 1 in every 91,806 girls born was named Unknown. STABLE Recent data shows the name is currently stable.