Cathasaigh is an extremely talented young singer and musician from Pittsburgh PA.
Ó Cathasaigh, anglicized O'Casey, is pronounced ó kah-a-see.It is translated as 'descendant of Cathasach'.
CathasaighANOTHER ANSWER:Cathasach (nominative) Cathasaigh (genitive).
The surname Casey is Irish. It is the shortened Anglicized form of Gaelic Ó Cathasaigh 'descendant of Cathasach', meaning 'vigilant' or 'noisy'.
D'Arcy is a French surname meaning 'from the village of Arcy' - it isn't Irish in origin.Actually, while D'Arcy is French, the Darcy surname has origins in Ireland too. The Irish for Darcy is Ó Dhorcaigh, or Ó Dhorchaidhe, which translated back into English means "Descendant of the Dark One".
If referencing to the surname, Ó Cathasaigh (masculine)Ní Chathasaigh (feminine)Pronounced: Oh Kah-as-ig and Nee Khah-as-igAnother answer:In case you are asking about a first name the Irish name Caisín [kasheen] is similar and was used for males and females. It means 'curly-haired'.