An Etymological Dictionary of the German Language/Annotated/Koppel

by Friedrich Kluge

Koppel, feminine and neuter, ‘leash,’ from Middle High German koppel, kopel, kuppel, feminine (masculine and neuter), ‘tie, connection,’ especially ‘leash,’ then collective ‘pack of hounds,’ also ‘band’ generally; from Latin copula, Middle Latin also cupla (the latter also ‘couple of hounds in a leash’), whence also French couple, English couple, Dutch koppel, ‘couple, multitude, troop.’