Sidni is a distinctive girls' name in United States, ranking #5627 in 1999 with 19 recorded births. The name reached its all-time peak in 1999 with 19 births ranking #5627. Since 1996, the popularity has increased by 171.4%. In 1999, approximately 1 in every 93,357 girls born was named Sidni. FALLING Recent data shows the name is currently falling.