ZAIR (zā'ĭr, Heb. tsā‘îr, small). A village somewhere east of the Dead Sea in Idumea where Jehoram conquered the Edomites (2Kgs.8.21). It has not been identified with certainty.

ZAIR zā’ ər (Heb. צָעִ֔יר, prob. narrow place), a topological name derived from Heb. צָעַר, H7592, be narrow. It is mentioned only in 2 Kings 8:21, as the scene of the battle between Judah and its rebellious subject, Edom. Joram led his troops against the Edomite king and won the battle but permitted so many to escape that Edom was never again subjugated. The identification of this valley has never been proven, but the LXX rendering, Gr. Σειωρ, has been taken as an ancient form of modern Si’ir. The term is so imprecise, referring only to the width or circumference of the place, that a detailed location is so far impossible.

International Standard Bible Encyclopedia (1915)

When he invaded Edom, we are told that Joram passed over to Zair and all his chariots with him (2Ki 8:21). In the parallel passage (2Ch 21:9), "with his captains" (`im sarayw) takes the place of "to Zair" (tsa`irah), probably a copyist’s corruption. The place has not been identified. Some have thought that Mt. Seir is intended; others that it means the town of Zoar. Conder suggested ez-Zuweirah, Southeast of the Dead Sea. If Zoar lay in this direction, it is the way by which an invading army might enter Edom.