Lilly is a spelling variant of Lily, the flower name that comes from the Latin lilium and means "lily", a flower long associated with purity and with the Virgin Mary. Like Lily it also works as a pet form of Lillian and Elizabeth, and the double-l spelling has been used in England since the 19th century. Lilly rose from number 428 in 2000 to a US peak of number 103 in 2011 and has settled back to number 252 among girls' names in 2025.