ῥαχός

Etymology
Clearly related to. Since ϝρᾰχ-/ϝρᾱχ- cannot be derived from an Indo-European root, the word might instead be of origin.

Noun

 * 1) thorny bush, briar, brushwood
 * 2) thorn-hedge, wattled fence, palisade
 * 3)  twig, branch of the vine
 * 4)  wild olive tree