Syriac

puḥdā - thigh, buttocks (LSyr. 562, SL 1161)

PWS
*paḫiḏ- - hip, thigh (SED I No. 211, Kogan 2011: 225)
On the semantic shift ‘hip, thigh’ > ‘tribal union’ see Kogan-Militarev 2003 295-296.