An Etymological Dictionary of the German Language/Annotated/Zither
Zither, Cither, feminine, ‘guitar, zither’; formed like the equivalent Old High German cithara, zitera, feminine, from the equivalent Latin cithara. Middle High German has only zitôle, feminine, ‘zither,’ from Old French citole, which, like Italian cétera, comes from Latin cîthara. Italian and Spanish guitarra, whence French guitare, Modern High German Guitarre, ‘guitar,’ is, on the other hand, derived from Greek κιθάρα.