1Frequently in plural. A person of Scottish origin or descent born or resident in Ulster (now especially the six counties comprising Northern Ireland); specifically a Scottish person who settled in the north of Ireland during the Plantation of Ulster in the 17th century (historical); a descendant of such a settler.
2 historical, rare A Scot from Ulster; = Dalriadan .
Designating the Ulster Scots; of, relating to, or characteristic of the Ulster Scots.
Mid 17th century. From Ulster + Scot.