Smith's Dictionary
(abundance), one of the cities of Judah in the low country, the Shefelah, (Joshua 15:42) allotted to Simeon. (Joshua 19:7)
International Standard Bible Encyclopedia
e'-ther (`ether; Ather):
A town in Judah (Jos 15:42), near Libnah, assigned to Simeon (Jos 19:7). Kh. el `Atr (identical in spelling with Ether) is possibly the site.
It is near Beit Jibrin and is described as "an ancient site: cisterns, foundations, quarried rock and terraces" (PEF, III, 261, 279).