Here is MacLysaght (Surnames of Ireland) on the name:"(O) MORONEY. Properly 'Ó Maolruanaidh', now often corrupted to 'ÓMurruanaidh.
This Clare name has spread to Kerry. See Mulrooney.""(O) Mulrooney. 'Ó Maolruanaidh'. A once powerful sept subjugated by theMaguires; in Fermanagh the name is still found in small numbers.
In Co.Galway it has been changed to Moroney. Map Fermanagh, Galway. See Rooney."(O) Rooney. 'Ó Ruanaidh'. Originating in Co. Down, where Ballyrooney locatesthem, this name is now numerous in all the provinces except Munster.
In west Ulster and north Connacht Rooney is often an abbreviation of Mulrooney. (O) Rooney, Roonian. 'Ó Rúnaidhin'.
This name, which is closely associated with north Leitrim and south Donegal, has often been absorbed by Rooney.O'Donovan records the Irish form in Co. Sligo as 'Ó Rúnaighean'."Bell (Book of Ulster Surnames) says much the same and adds a little interest:,
He says the name ROONEY appears often in the ecclesiastical annals and history of the diocese of Dromore, but it is as a literary family that the yare most famous. Ceallach O'ROONEY, died 1079, was styled Chief Poet of Ireland. Eoin O'ROONEY, died 1376, was chief poet to MacGUINNESS of Iveagh.William ROONEY, 1873-1901, was a noted poet who was involved in Gaelicrevival of the late nineteenth century.
At that time the name was found to be synonymous with ROWNEY around Newery in Co. Down and with ROOHAN andRUNIAN near Ballyshannon in Co. Donegal.
He adds, "There are two different origins for Rooney in Co. Fermanagh and adjacent areas. The Mac Maolruanaigh were Kings of Fermanagh before theMaguires. Their name was anglicised as Mulrooney, then Rooney. The distinct septs of Maolruanaigh were lords of Clankelly as early as 1296.
This name was anglicised as Macarooney and was rendered thus in the late nineteenth century. It has been shortened to Rooney."