Oakum treated with tar or other substances; material used for caulking ships and sealing wooden structures.
From coak (wooden peg) plus -um suffix, or possibly from old maritime terminology. Related to the nautical term oakum (tarred rope fibers).
Coakum was the duct tape of the sailing age—sailors mixed tarred fibers with oakum to waterproof ship seams, and the smell of coakum meant a ship was being properly maintained.
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