Easton's 1897 Bible Dictionary:

Jeshimon
   the waste, probably some high waste land to the south of the
   Dead Sea (Num. 21:20; 23:28; 1 Sam. 23:19, 24); or rather not a
   proper name at all, but simply "the waste" or "wilderness," the
   district on which the plateau of Ziph (q.v.) looks down.


Hitchcock's Bible Names Dictionary (late 1800's):

Jeshimon, solitude; desolation