Shur

"An enclosure; a wall, a part, probably, of the Arabian desert," "on the north-eastern border of Egypt, giving its name to a" wilderness extending from Egypt toward Philistia (Gen. 16:7; 20:1; 25:18; Ex. 15:22). The name was probably given to it from the wall (or shur) which the Egyptians built to defend their frontier on the north-east from the desert tribes. This wall or line of fortifications extended from Pelusium to Heliopolis.

Definition of Shur:
"wall; ox; that beholds"