Derived words: mušapšiḳtu ‘having difficulty (in childbirth)’ (CAD M₂ 259); muštapšiḳtu (multapšiḳtu) ‘having difficulty (in childbirth)’ (CAD M₂ 285); pašḳiš ‘with difficulty’ (CAD P 257, AHw. 845); pašḳu ‘narrow; difficult; dangerous’ (CAD P 257, AHw. 845); pašuḳtu ‘difficulty, hardship’ (CAD P 269); pušḳānu (a person with a characteristic feature) (CAD P 543, AHw. 883); pušḳu ‘distress, constriction’ (CAD P 543, AHw. 883); šapšāḳu ‘constraint, hardship’ (CAD Š₁ 482, AHw. 1176); šupšuḳtu ‘woman having difficulty (in childbirth)’ (CAD Š₃ 327, AHw. 1280); šupšuḳu ‘very narrow, difficult’ (CAD Š₃ 327, AHw. 1281).
This specifically Akkadian root has no reliable Semitic etymology. Cf. perhaps Arb. fašaq- ‘distance between two horns or two teats’.