An Etymological Dictionary of the German Language/Annotated/gewiß

by Friedrich Kluge

gewiß, adjective and adverb, ‘sure(ly), certain(ly), confident(ly),’ from the equivalent Middle High German gewis(ss), adjective, gewisse, adverb, Old High German gewis(ss), adjective, gewisso, adverb, ‘certain, sure, reliable’; corresponding to Dutch wis, gewis; Goth only in unwisa- (misspelt for *unwissa), ‘uncertain.’ The Old Teutonic wissa (gawissa-) is an old participle of the Gothic pret.-pres. witan, Old High German wiȥȥan (see wissen), from witta-, widto- (allied to the Aryan root vid). With regard to the pregnant meaning, ‘what is certainly known,’ for ‘what is known,’ compare laut, literally ‘what is heard.’