Smith's Bible Dictionary (1863)
(strong or stony), one of the places from which some of the captivity returned with Zerubbabel to Judea who could not show their pedigree as Israelites.
Hastings' Dictionary of the Bible (1898) & Schaff's Bible Dictionary
AD'DAN (stony), Ezr 2:59; called also Addon. Neh 7:61. Its site is unknown.