Ó Cathasaigh

== Irish == === Etymology === From Ó + Cathasach, a given name derived from Old Irish cathaisech (“vigilant; noisy”) (compare cathaiseach). === Pronunciation === IPA(key): /oːˈkahəsˠiː/ === Proper noun === Ó Cathasaigh m (genitive Uí Chathasaigh) a male surname originating as a patronymic, feminine equivalent Ní Chathasaigh, equivalent to English Casey === References === MacLysaght, Edward (1985), “(O) Casey”, in The Surnames of Ireland, sixth edition, Dublin: Irish Academic Press, →ISBN, page 40; reprinted 1999