An Etymological Dictionary of the German Language/Annotated/Kork
Kork, masculine, ‘cork,’ early Modern High German only, through the medium of Dutch (kork, kurk, neuter, ‘corkwood, cork, stopper’) and Low German commerce, from Spanish corcho, ‘corkwood, stopper,’ whence also English cork at an early period. The ultimate source is Latin cortex, ‘bark.’