|Easton's Bible Dictionary|
Place of abundance, a place on the east of Jordan and west of the Euphrates where David gained a great victory over the Syrian army (2 Samuel 10:16), which was under the command of Shobach. Some would identify it with Alamatta, near Nicephorium.
Int. Standard Bible Encyclopedia
he'-lam (chelam, 2 Samuel 10:16; in 16:17 with the he of locale; Septuagint Hailam): A place near which David is said to have defeated the Aramean world under Hadarezer (2 Samuel 10:16). Its site is unknown. Cornill and others introduce it into the text of Ezekiel 47:16 from the Septuagint Heliam). This would place it between the territories of Damascus and Hamath, which is not unreasonable. Some scholars identify it with Aleppo, which seems too far north.
Helam (3 Occurrences)
2 Samuel 10:16 Hadadezer sent, and brought out the Syrians who were beyond the River: and they came to Helam, with Shobach the captain of the army of Hadadezer at their head. (WEB KJV JPS ASV BBE DBY WBS YLT NAS RSV NIV)
2 Samuel 10:17 It was told David; and he gathered all Israel together, and passed over the Jordan, and came to Helam. The Syrians set themselves in array against David, and fought with him. (WEB KJV JPS ASV BBE DBY WBS YLT NAS RSV NIV)
1 Chronicles 19:17 And word of this was given to David; and he got all Israel together and went over Jordan and came to Helam and put his forces in position against them. And when David's forces were in position against the Aramaeans, the fight was started. (BBE)