puḫḫu - to exchange (CAD P 482, AHw. 876)

Derived words: pāḫu ‘substitute’ (CAD P 20, AHw. 877); pūḫu ‘substitute’ (CAD P 496, AHw. 877); pūḫtu ‘substitute’ (CAD P 493, AHw. 877).
No definitive etymology can be suggested as no suitable Semitic parallels have been detected.