Akkadian

ḳīštu - forest, wood (CAD Q 272, AHw. 923)

Though not bein attested before OB period this word has a transparent correspondence in Ebla: ḳá-sa-tum.

PS
*ḳayŝ- - forest, wood (Fronzaroli 1969a: 277, 290; Kogan 2011: 200; Kogan 2012: 230)