Benayim means the space between two things — an interval or middle ground. It is a dual form related to bayin or ben ("between"). In military contexts, it refers to the no-man's-land between two opposing armies where champions would meet for single combat.
The word appears in one of the most dramatic scenes in all of Scripture: Goliath stepping into the benayim — the space between the Israelite and Philistine battle lines — to issue his challenge (1 Samuel 17). The "man of the between" (ish ha-benayim) was the champion who fought in the gap. David's willingness to enter that space, armed only with a sling and the name of the LORD, prefigures Christ who entered the ultimate space between God and humanity to fight on our behalf.