An Etymological Dictionary of the German Language/Annotated/Knebel
Knebel, masculine, ‘branch, peg, moustache, knuckle,’ from Middle High German knębel, masculine, Old High German knębil, ‘crossbeam, girder, crossbar, cord, fetter, knuckle’; Dutch knevel, masculine, ‘packing stick’; Scandinavian knefill, masculine, ‘stake, stick’; Gothic *knabils is wanting. Considering the relation of Gothic *nabala, masculine, ‘navel,’ to Greek ὀμφαλός, we may assume for Gothic *knabils, a root gombh (gonbh) in the non-Teutonic languages (compare γόμφος, ‘plug, nail, wedge’; this word, however, is usually connected with the cognates of Modern High German Kamm). — It is still doubtful whether Knebel in Knebelbart ‘(twisted) moustache,’ first recorded in Modern High German and borrowed from Low German and Dutch, is of a different origin, i.e. connected with Anglo-Saxon cęnep, Old Frisian kenep, Old Icelandic kanpr (Gothic *kanipa-), ‘moustache,’ Middle Dutch canefbeen, ‘cheek-bone.’