An Etymological Dictionary of the German Language/Annotated/Bann
Bann, masculine, ‘ban, outlawry, decree,’ from Middle High German and Old High German ban (nn), masculine, ‘order under threat of punishment, prohibition; jurisdiction and its sphere.’ It corresponds to Anglo-Saxon bann, English ban, and belongs to an obsolete strong verb bannan, of which the primary meaning was ‘to order or forbid under threat of punishment.’ The root is supposed to be ba, pre-Teutonic bha-; nn was perhaps a suffix (compare rinnen), and properly belonged only to the present of the strong verb, but was afterwards joined to the verbal stem. To this pre-Teutonic bha- belongs, in accordance with the permutation of consonants, Greek φα in φά-σκω, φη-μί and Latin fa in fari; the Teutonic meaning must then have been very definitely specialised. From the Teutonic word the Romance cognate French ban, ‘public proclamation’ (Old French arban, ‘arrière ban’), is derived.