A person who caulks (seals seams in boats or structures), or a dialectal term related to chalk work.
From 'calk' or 'caulk' (to seal seams) + '-er' suffix (one who does the action), or possibly related to obsolete 'cawk' with agent noun formation.
A cawker was essential on every ship before modern materials—they literally held wooden vessels together by hammering fibrous material into seams, a skill that took years to master!
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