From Irish Names and Surnames 1923
Ó CADHLA—I—O Keyle, O Kealy, O Quealy, Kiely, Keily, Kealy, Keely, Keeley, (Kelly), Quealy, &c.; 'descendant of Cadhla' (beautiful, comely, graceful); the name (1) of a Connacht family who were formerly chiefs of Connemara; and (2) of a Thomond family who were chiefs of Tuath Luimnigh in the neighbourhood of the city of Limerick. Both families are still numerously represented in Connacht and Munster. To be distinguished from Ó Caollaidhe, which see.
Alphabetical Index to Irish Surnames