This name derives from the Old English surname “Casley, Casely, Causley and Kesley”, Old English place name in Lincolnshire, England. The origin of this name is still today quite uncertain. The theories include: 1) From the Old English “catt / catte”, from the Late Egyptian “čaute / čaus” (masculine and feminine cat) plus “lēah” (meadow, forest clearing). 2) From the Irish Gaelic “Cathasaig”, meaning “vigilant, watchful”, from the surname “Ó Cathasaig”. In turn the name means “descendent of Cathasach”.