Mcguinness — Lords of Iveagh

McGuinness comes from Mag Aonghusa, built on the personal name Aonghus (see also Hennessy, from the same root by a different route). The family ruled Iveagh, the largest and most powerful lordship in medieval Down, for some four centuries before the Ulster Plantation broke their power.

A name that once ruled the biggest territory in its county — proof that even the grandest Gaelic lordships eventually answered to the same plantation as the smallest.

Irish form: Mag Aonghusa