An Etymological Dictionary of the German Language/Annotated/Kissen
Kissen, Küssen, neuter, ‘cushion,’ from Middle High German küssen, küssîn, Old High German chussī̆n, neuter, ‘cushion’; compare Dutch kussen, ‘cushion.’ The German word is derived (compare Pfühl and Flaum) from the equivalent Middle Latin cussînus (French coussin), which comes from Latin *culcitinum, allied to culcita, ‘mattress, cushion’; English cushion and Italian cuscino are modern French loan-words. The i of Modern High German Kissen comes from Middle German and Upper German dialects (compare Pilz and Bims).