Metheg-ammah must be the name of some stronghold which commanded Gath, and the taking of which made David master of Gath and her towns.
Related Commentaries of 2 Samuel 8:1
2 Samuel 8:1
1 And after this it came to pass, that David smote the Philistines, and subdued them: and David took Methegammaha out of the hand of the Philistines.