Origin of the name Kayleigh: Transferred use of the Anglicized Irish surname, which is from the Gaelic Mac Caollaidhe (son of Caollaidhe) and O'Caollaidhe (descendant of Caollaidhe). The name is derived from caol (slender). Var: Kailee, Kaili, Kali, Kaylea, Kaylee. From A World of Baby Names by Teresa Norman.