De Liosla
de LIOSLA—XI—de l'isula, del Isle, Lisle, Lislie, Leslie, Lesley; Norman 'del Isle,' Latin 'de Insula,' i.e., of the island, from residence therein. A family of this name came to Ireland about the time of the Anglo-Norman invasion and seem to have settled in Dublin and Meath. Some Scottish Leslies settled in Derry at the time of the plantation of Ulster.
Alphabetical Index to Irish Surnames