ED ("witness"):
Name supplied by the English versions for the altar erected by the tribes on the east of the Jordan (Joshua xxii. 34). The name does not appear in the Masoretic text nor in the Septuagint. The Hebrew reads simply, "And the children of Reuben and the children of Gad called the altar, for it is a witness between us that the Lord is God"; and it would seem that the name of the altar must have been dropped by a copyist.
Dillmann (Joshua ad loc.) suggests "Gal-'ed," as in Gen. xxxi. 47 (A. V. "Galeed").