This name, which was found to be twelfth most numerous in its homeland of Co. Monaghan in 1970, is almost exclusive to the south of that county, Armagh and Louth.  The name in Gaelic was Mac Ardghail, from ardghal, meaning 'high valour'.

They are a branch of the MacMahons of Oriel, forst noted as Sliocht Ardghail Mhóir Mhic Mathúna, 'the stock of Ardghal Mór MacMahon', who was chief of the MacMahons from 1402 to 1416.  They were based originally in the barony of Monaghan and a branch became sub-chiefs in Armagh under the O'Neills of the Fews.

The early-eighteenth-century Gaelic poet James MacArdle was of the Fews district.  He was a contemporary of poet Patrick MacAlinden who was married to the poet Siobhán Nic Ardghail (Johanna MacArdle).



Clan From the Gaelic clann which means literally 'children'.
Mac- From the Gaelic mac, meaning 'son'
O' From the Gaelic Ó, meaning 'grandson', 'grandchild' or 'descendant'; Ní is the femine form of Ó, meaning 'daughter' or 'descendant'
Plantation (Ulster) The redistribution of escheated lands after the defeat of the Ulster Gaelic lords and the 'Flight of the Earls' in 1607.  Only counties Donegal, Derry, Tyrone, Armagh, Fermanagh and Cavan were actually 'planted', portions of land there being distributed to English and Scottish families on their lands and for the building of bawns.
Sept A family group of shared ancestry living in the same locality
Undertakers Powerful English or Scottish landowners who undertook the plantation of British settlers on the lands they were granted.
Gaelic This word in Ireland has no relation to Scotland.  As a noun it is used to denote the Irish language, as an adjective to denote native Irish as opposed to Norman or English origin.
Erenagh From the Irish Gaelic airchinneach, meaning 'hereditary steward of church lands'.  A family would hold the ecclesiastical office and the right to the church or monastery lands, the incumbent at any one time being the erenagh.