From BiblePortal Wikipedia

Smith's Bible Dictionary [1]

Ra'math-le'hi. (hill of the jawbone or hill of Lehi). The name bestowed by Samson, on the scene of his slaughter of the thousand Philistines, with the jaw bone,  Judges 15:17, a place by the rock Elam, in western Judah of the Philistines.

Morrish Bible Dictionary [2]

See Lehi.