Boyd’s Bible Dictionary:
(witness). A word (Josh. 22:34).
Concise Bible Dictionary:
This word, signifying “witness,” is added in the AV in Joshua 22:34. Instead of “called the altar Ed,” it has been translated “gave a name to the altar.” The word “Ed” is in some Hebrew MSS, and in the Syriac and Arabic versions, but not in the LXX.
Jackson’s Dictionary of Scripture Proper Names:
a witness