Akkadian

šuršu - root, base, foundation (CAD Š₃ 363, AHw. 1286)

PS
*ŝVrš- - root (Kogan 2015:42)
This conventional reconstruction does not pretend to describe with full adequacy all the extant cognates. Problems connected with the reconstruction of the PS term for “root” are extensively discussed in Faber 1984:213‒219. (Kogan 2015:42, note 99)