PCS

*nγṣ̂ - to shake (Renfroe 1992:62‒64; Kogan 2015: 320)

Ugr-Arb exclusive isogloss

Ugaritic
nγṣ - to contract, shake; to buckle (DUL 625)
Arabic
nγḍ - to be in motion, convulsion; to totter (Lane 2818)