An Etymological Dictionary of the German Language/Annotated/Zitter
Zitter, Zieter, feminine, ‘thill, shaft,’ from the equivalent Middle High German zieter, Old High German ziotar, zieter, masculine and neuter. The latter can hardly represent *ziohtar (allied to ziehen) on account of Anglo-Saxon teóder, English tether, Old Icelandic tjóðr, ‘rope.’ The unintelligible Modern High German word was popularly, but wrongly, connected with zittern (dialectic Zetter, Zitterstange).