ῥίσκος

Etymology
Probably a loanword. According to Donatus, it is of origin, a path followed by Thumb, who considers  to be the ultimate source, comparing 🇨🇬. The word would have reached Greek from Galatian, through Phrygian because of the change u > i. Anyway, Beekes doesn't dismiss a origin.

Noun

 * 1) coffer, chest, especially for plate or money