Cassidy is a distinctive girls' name in England & Wales, ranking #686 in 2015 with 59 recorded births. The name reached its all-time peak in 2010 with 67 births ranking #586. Since 1996, the popularity has increased by 268.8%. In 2015, approximately 1 in every 5,219 girls born was named Cassidy. FALLING Recent data shows the name is currently falling.