An Etymological Dictionary of the German Language/Schwibbogen
Schwibbogen, m., ‘stone arch, arcade, flying buttress,’ from MidHG. swiboge, OHG. swibogo, m.; the ModHG. form is an early corruption, connecting sweiboge, which had become obscure even in MidHG., with schweben and Bogen. OHG. swibogo, ‘arched vault,’ if this too is not a corruption, appears to be either an old derivative from the root swib (see schweben), hence Goth. *swib-uga, or a compound of OHG. bogo, ‘bow, arch,’ with a prefix swi-, the meaning of which is certainly not clear; comp. Goth. swi-kunþs, ‘manifest,’ OIc. sve-víss (?), svi-dauðr (?), AS. sweo-tol.