caulk BrE AmE ( also calk American English ) /kɔːk $ kɒːk/ verb [transitive]
[ Date: 1400-1500 ; Language: Old North French ; Origin: cauquer 'to press down with the feet' , from Latin calcare , from calx 'heel' ]
to fill the holes or cracks in a ship with an oily or sticky substance in order to keep water out