Rinn: a river in Conalle Murthemni
Rogne: a territory between the rivers Suir and Barrow, in the barony of Kells, the County Kildare or Kilkenny
Ross: a district in the south of the County Monaghan
Ross Mor: probably Ross na Rig, near Ball Scena
Sas: a river in Conalle Murthemni
Scathach: the Amazon dwelling in Alba who taught Cuchulain and Ferdiad their warlike feats (pronounced Scaw-ha)
Selaig: Sheelagh, a townland in the barony of Upper Dundalk
Semne: Island Magee, north-east of Carrickfergus, in the County Antrim
Senbothae: Templeshanbo, at the foot of Mount Leinster, in the County Wexford