From Longman Dictionary of Contemporary Englishcaulkcaulk (also calk American English) /kɔːk $ kɒːk/ verb [transitive] REPAIRto fill the holes or cracks in a ship with an oily or sticky substance in order to keep water out→ See Verb table
Examples from the Corpus
caulk• You may need to make other repairs, such as repointing or replacing damaged wood, siding or masonry before you caulk.• The trouble was that the company that would eventually caulk and waterproof the building had not yet been appointed.• As a favor, the masons at the test site had said they would do the caulking of the mockup.Origin caulk (1400-1500) Old North French cauquer “to press down with the feet”, from Latin calcare, from calx “heel” 