Comments:Владимирцов 258, АПиПЯЯ 13, 19, 49-50, 70, 285, Дыбо 11. Mong. dabu-su regularly < *dabur-su; borrowing in Mong. < Turk. is absolutely improbable, despite Щербак 1997, 160. The Turk.-Mong. parallel is an old etymology (starting with Pelliot 1935, 231) which Doerfer (TMN 2, 510-511) tries in vain to refute. A small problem is the preservation of *-b- (one should rather expect *daɣu(r)-sun in Mong.), which should be probably explained by an old assimilation *či̯obeŕV- > *či̯opeŕV in pre-PM. For Jpn. one has to assume a rather universal semantic change 'bitter' > 'hard, unbearable'. Cf. perhaps also MKor. čùijǝ̀mí 'vinegar dregs'.