The River Dee is a river in eastern Ireland, flowing from County Cavan to flow into the River Glyde near the coast, in County Louth. In the Táin Bó Cúailnge, Cúchulainn fights Ferdia at Ath Carpat on the river Níth. The river takes its name from the Irish níth, meaning "combat". The modern name Dee derives from the town of Ardee.