Easton's Bible Dictionary (1897)
One of the royal cities of the Canaanites, now ‘Aid-el-ma (Josh. 12:15; 15:35). ), which was the scene of David’s memorable victory over Goliath (1 Sam. 17:2), and not far from Gath. It was one of the towns which Rehoboam fortified against Egypt (2 Chr. 11:7). It was called “the glory of Israel” (Micah 1:15). The Cave of Adullam has been discovered about 2 miles south of the scene of David’s triumph, and about 13 miles west from Bethlehem.
At this place is a hill some 500 feet high pierced with numerous caverns, in one of which David gathered together “every one that was in distress, and every one that was in debt, and every one that was discontented” (1 Sam. 22:2). Some of these caverns are large enough to hold 200 or 300 men. According to tradition this cave was at Wady Khureitun, between Bethlehem and the Dead Sea, but this view cannot be well maintained.
Smith's Bible Dictionary (1863)
(justice of the people), Apocr. Odollam, a city of Judah int he lowland of the Shefelah, (Joshua 15:35) the seat of a Canaanite king, (Joshua 12:15) and evidently a place of great antiquity. (Genesis 38:1,12,20) Fortified by Rehoboam, (2 Chronicles 11:7) it was one of the towns reoccupied by the Jews after their return from Babylon, (Nehemiah 11:30) and still a city in the time of the Macabees. 2Ma 12:38 Adullam was probably near Deir Dubban, five or six miles north of Eleutheropolis.
The limestone cliffs of the whole of that locality are pierced with extensive excavations, some one of which is doubtless the “cave of Adullam,” the refuge of David.
Hastings' Dictionary of the Bible (1898)
ADUL'LAM (justice of the people, or biding, or resting-place), a cave not far from Bethlehem in which David hid. 1 Sam 22:1; 2 Sam 23:13; 1 Chron 11:15. Tradition has located it in Wady Khureitun, east of Bethlehem. The cave is said to be well fitted for a robbers' hold, being dry and airy and full of intricate passages. The greatest length of this cave is 550 feet. Lieut. Conder, however, places the cave of Adullam in the valley of Elah, not far from the city of Adullam, about 13 miles west from Bethlehem.
Near it are numerous caverns, each as large as an ordinary cottage, which would give room for David and his band. He states that the great caverns at Beit Jibrin, which some have regarded as the cave of Adullam, are damp, cold, and full of bats and creeping things, and carefully avoided by the cave-dwelling peasants, while the smaller caves north and west of Adullam are almost constantly in use, and are from their position strong and defensible. A row of these caves has been found north and west of the city of Adullam capable of holding 200 to 300 men. M.
Ganneau first suggested this location in 1872, from the resemblance of the modern name Aid el-Ma, and it seems to answer the requirements of the Scripture narrative.
Hastings' Dictionary of the Bible (1898) & Schaff's Bible Dictionary
ADUL'LAM, a royal city of the Canaanites allotted to Judah, Gen 38:1 ; Gen Josh, 12 : 15 ;Gen 15:35 ; fortified by Rehoboam, 2 Chr 11:7 repeopled by the Jews after the Captivity, Neh 11:30. See also Mic 1:15. Ganneau and Conder locate it in Wady es-Sent, about 2 1/2 miles south of Socoh or Shucoh, where they found heaps of stones and ruined walls, called Aid el-Ma.
Hitchcock's Bible Names (1869)
their testimony; their prey; their ornament