PS

*kVsl- - lower part of the trunk, genitals (SED I No. 153; Kogan 2011: 218)

Akkadian
kislu - transverse process of the vertebra (CAD K 425, AHw. 486)
Var. kaslu.
Ebla
ga-za-um /kas(a)Lum/ - back (VE 665, Kogan–Krebernik 2021b: 687)

Var. gi-za-um /kis(a)Lum/ (EV 359)

Ugaritic
ksl - back (DLU 226)
also means ‘bowstring’, parallelled by Arb. kisl- (Held 1965: 401–406)
Hebrew
käsäl - loins; genitals (HALOT 489)
Jewish Palestinian Aramaic
kslyn - loins (DJPA 265)
Jewish Babylonian Aramaic
kislā - loins (Jastrwo 654)
Arabic
kawsalat- - glans penis (WKAS I 194)
may be related