Words

Arabic
ksf - to split, to cut (BK 2 898)
Arabic
ksm - to crumble in one’s hand (LA 12 612)
Arabic
ksr - V. to break, to be broken (Lane 2611)
Arabic
ksw - to clothe (BK 2 889, Lane 3000)
Arabic
ḳṣd - not to exceed the due bounds, to act in a moderate manner, to walk in an equable, moderate pace (Lane 2531)
Arabic
kāšid- - one who earns, obtains much (LA 3 466)

Probably related

Arabic
ktb - to write (Lane 2589)
Arabic
ktb - to sew together (Lane 2589)
Arabic
katif- - shoulder-blade, shoulder (BK 2 862, Lane 2998)
Arabic
kuttān- - sorte d'insecte rouge et dont la picûre est douloureuse (a kind of red insect whose sting is painful) (BK 2 864, WKAS K 55)
Related with metathesis?