An Etymological Dictionary of the German Language/Annotated/Schlüssel

by Friedrich Kluge

Schlüssel, masculine, ‘key,’ from the equivalent Middle High German slüȥȥel, Old High German sluȥȥil, masculine; corresponding to Old Saxon slutil, Dutch sleutel. This derivative of schließen (Gothic *slutila-) is wanting in English, Old Icelandic, and Gothic.