From BiblePortal Wikipedia

Fausset's Bible Dictionary [1]

A town in Judah, on a height overlooking the Shephelah or low hill country ( Joshua 15:36). Probably the same as that called later Hadid and Adida . Vespasian used the latter as one of his outposts in besieging Jerusalem.

Smith's Bible Dictionary [2]

Aditha'im. (Double Ornament). A town belonging to Judah, lying in the low country, and named, between Sharaim and hag-Gederah, in  Joshua 15:36 only.

Hastings' Dictionary of the Bible [3]

Adithaim (  Joshua 15:36 ). A town of Judah in the Shephelah. The site is unknown.

Morrish Bible Dictionary [4]

Town in the tribe of Judah.  Joshua 15:36 . It cannot be identified.

Holman Bible Dictionary [5]

 Joshua 15:36

Cyclopedia of Biblical, Theological and Ecclesiastical Literature [6]

(Heb. Aditha yim, עֲדַיתִיַם , Double Prey or Double Ornament; Sept. Ἀδιαθάϊμ , but some copies omit; Vulg. Adithaim), a town in the plain of Judah, mentioned between Sharaim and Gederah ( Joshua 15:36). Eusebius (Onomast. s.v.) mentions two places of the name of Adatha ( Ἀδαθά , Jerome, Aditha and Adia), one near Gaza, and the other near Diospolis (Lydda); the former being commonly supposed to be the same with Adithaim, and the latter with Hadid; and probably corresponding respectively to the two places called Adida (q.v.) by Josephus. Schwarz (Palest. p. 102) accordingly thinks that Adithaim is represented by the modern village Eddis, 5 Eng. miles east of Gaza (comp. Robinson s Researches, 2, 370 sq.); but this is too far from the associated localities of the same group, (See Tribe),which require a position not far from Moneisin, a village with traces of antiquity, about 5 miles south of Ekron (Van de Velde, Memoir, p. 114).

International Standard Bible Encyclopedia [7]

ad - i - thā´im ( עדיתים , ‛ădhı̄thayim "double ornament, passage, or prey"): A city in "the lowland" (Shephelah, not as the King James Version "valley ") of Judah ( Joshua 15:36 ). Site unknown, but possibly same as Adida (which see).