From BiblePortal Wikipedia

Hastings' Dictionary of the Bible [1]

Eleutherus ( 1Ma 11:7; 1Ma 12:30 ). A river which separated Syria and PhÅ“nicia, and appears to be the mod. Nahr el-Kebîr or ‘Great River,’ which divides the Lebanon in two north of Tripoli.

Cyclopedia of Biblical, Theological and Ecclesiastical Literature [2]

( Ε᾿Λεύθερος , Free; see Simonis, Onom. page 58), a river of Syria mentioned in  1 Maccabees 11:7;  1 Maccabees 12:30. In early ages it was a noted border stream (Pliny, 5:17; 9:12; Ptolemy, 5:15, 4). According to Strabo, it separated Syria from Phoenicia (16:753), and formed the northern limit of Coele-Syria. Josephus informs us that Antony gave Cleopatra "the cities that were within the river Eleutherus, as far as Egypt, except Tyre and Sidon" (Ant. 15:4, 1; War, 1:18, 5). A careful examination of the passages in  Numbers 34:8-10, and  Ezekiel 47:15-17, and a comparison of them with the features of the country, lead Mr. Porter to the conclusion that this river also formed in part the northern border of the " Promised Land" (Five Years In Damascus, 2:354 sq.). Pliny says that at a certain season of the year it swarmed with tortoise (9:10). Of the identity of the Eleutherus with the modern aihr el-Kebir, "Great River," there cannot be a doubt. Its highest source is at the northeastern base of Lebanon; it sweeps round the northern end of the range, through the opening called in Scripture "the entrance of Hamath" ( Numbers 34:8), and, after receiving several small tributaries from the heights of Lebanon, it falls into the Mediterranean about eighteen miles north of Tripolis. It still forms the boundary between the provinces of Akkar and elHusn. During summer and autumn it is but a small stream, easily forded, but in winter it swells into a large and rapid river (Maundrell, p. 33; Burckhardt, page 270; Paulus, Samml. 1:35, 303).

International Standard Bible Encyclopedia [3]

ē̇ - lū´thẽr - us ( Ἐλεύθερος , Eleútheros  ; 1 Macc 11:7; 12:30): A river separating Syria and Phoenicia.