An Etymological Dictionary of the German Language/knüpfen

by Friedrich Kluge

knüpfen, vb., from the equiv. MidHG. knüpfen, OHG. knupfen, ‘to unite, tie, fasten together’ (Goth. *knuppjan is wanting); a nominal vb. from Knopf, which see; MidHG. knopf, ‘knot.’