northernmost of the four provinces of Ireland, 14c., from Anglo-French Ulvestre (early 13c.), Anglo-Latin Ulvestera (c. 1200), corresponding to Old Norse Ulfastir, probably from Irish Ulaidh "men of Ulster" + suffix also found in Leinster, Munster, and perhaps representing Irish tir "land."[Ulster etymology, Ulster origin, 英语词源]