Cassidy is a distinctive girls' name in England & Wales, ranking #681 in 2008 with 53 recorded births. The name reached its all-time peak in 2010 with 67 births ranking #586. Since 1996, the popularity has increased by 231.3%. In 2008, approximately 1 in every 5,958 girls born was named Cassidy. FALLING Recent data shows the name is currently falling.