Комментарии:SKE 83, Lee 1958, 111, МССНЯ 356, ОСНЯ 1, 225. One of the few PA monosyllabic roots. The relation of the Turk. form is somewhat dubious (for semantic and phonetic reasons). One may conjecture that the original shape was PT *Ka- - actually attested in OT, see EDT 578 - which was early substituted by *Ko- under the influence of the more widespread *Kod- and then disappeared altogether.
