An Etymological Dictionary of the German Language/Annotated/kein

by Friedrich Kluge

kein, numeral adjective, ‘no, none,’ from Middle High German kein, shortened from dechein, Old High German dihhein, also Old High German dohh-ein, nihhein, nohhein, all of which are compounded with ein. The meaning of Old High German and Middle High German dech is obscure.