Nahr al-Kabir al-Janoubi (Arabic النهر الكبير الجنوبي 'the southern great river') is a river in the Syria and Lebanon flowing into the Mediterranean Sea at Arida, Lebanon. The river is 77.8km long, and drains a watershed of 954km2. Its headwaters are at the Ain as-Safa spring in Lebanon and it flows through the Homs Gap. In English, it is also known as the Nahr el-Kebir or simply as the Kebir.
The river forms the northern part of the border between Lebanon and Syria. In antiquity, the river was known as Eleutherus (Greek Ελεύθερος Eleutheros, Ελευθερίς Eleuteris lit. 'free'). It defined the border between the Seleucid and Ptolemaic empires during much of the 3rd century BCE.
The river is mentioned by Josephus and in 1 Maccabees 11:7 and 12:30.
Coordinates: 34°38′02″N 35°58′32″E / 34.63389°N 35.97556°E