Akkadian

rakābu - to mount, to mate (CAD R 83, AHw. 944)

Derived words: rikibtu ‘sexual intercourse, mounting’ (CAD R 344, AHw. 984).

*rkb - to ride; to (be) join(ed), connect(ed); to mount (SED I No. 60ᵥ; Kogan 2015: 457)