Kelsie is a variant of Kelsey, an English surname taken from place names in Lincolnshire; it is usually explained as "Cenel's island", from an Old English personal name meaning "fierce" and eg, island. Kelsey and its spellings were among the big girls' names of the late 1980s and 1990s. Kelsie reached its peak at number 441 in 2000 and has slipped out of the top 1000 since, ranking number 2248 in 2025.