An Etymological Dictionary of the German Language/Annotated/Seite
Seite, feminine, ‘side, flank, page,’ from Middle High German sîte, sît, Old High German sîta (sîtta), feminine, ‘side’; compare Dutch zijde, feminine, ‘side,’ and the equivalent Anglo-Saxon sîde, English side, Old Icelandic síða, feminine; Gothic *seidô (*seidjô), feminine, is wanting. Allied to Old Icelandic síðr, ‘hanging down,’ Anglo-Saxon sîd, adjective, ‘wide, large, extended’? — seits, in einerseits, ander-, jenseits, &c., with adverb s from Middle High German -sît in einsît, ander-sît, jënsît, which are accusative adverbs.