Unknown is a distinctive girls' name in United States, ranking #4440 in 2001 with 28 recorded births. The name reached its all-time peak in 2009 with 84 births ranking #2334. Since 1996, the popularity has decreased by 47.2%. In 2001, approximately 1 in every 64,306 girls born was named Unknown. STABLE Recent data shows the name is currently stable.