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