Akkadian

nayabtu - floating rib or cartilage at the tip of the rib (CAD N₁ 151, AHw. 717)

According to von Soden, nayyābu ‘ein innerer Körpert. nahe der Galle’ (AHw. 717).

PS
*nayab- - canine tooth (SED I No. 203)
Level?