Oakum n. : The material obtained by untwisting and picking into loose fiber old hemp ropes; -- used for calking the seams of ships, stopping leaks, etc.

Oakum n. : The coarse portion separated from flax or hemp in nackling.

Example:
What is the difference between white Oakum and brown Oakum?

Taxonomy
White oakum, free encyclopedia, joints, plumbing, wooden vessels, search, packing, timbers, deck planking, iron and steel, steel ships, cast iron, one time, tarry, ropes, cordage, occupation, virgin hemp.

Defination from the web:
Oakum is a preparation of tarred fibre used in shipbuilding, for caulking or packing the joints of timbers in wooden vessels and the deck ... Oakum was at one time made from old tarry ropes and cordage of vessels, and its picking and preparation has been a common penal occupation in ...