An Etymological Dictionary of the German Language/Knoblauch
Knoblauch, m., ‘garlic,’ from MidHG. knobelouch, m., with the orig. variant klobelouch, m., OHG. chlobolouh, chlofolouh, chlo volouh, m.; with regard to b for f, comp. Schwefel; the kn of the MidHG. and ModHG. words may be explained as in Knäuel by a process of differentiation, i.e. the l of the next syllable produced the change of the first l into n, comp. ModDu. knoflook and MidLG. kloflôk. In the ordinary explanation of ‘cleft leek’ no regard is paid to the fact that the first part of the compound, which is identical with ModHG. Kloben, appears elsewhere in the Teut. group, AS. clufe, E. clove (of garlic), AS. clufþung, ‘crowfoot,’ clufwyrt, ‘buttercup.’