oa·kum /ˈokəm/
  填絮
  Oak·um n.
  1. The material obtained by untwisting and picking into loose fiber old hemp ropes; -- used for calking the seams of ships, stopping leaks, etc.
  2. The coarse portion separated from flax or hemp in nackling.
  White oakum, that made from untarred rope.
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  oakum
       n : loose hemp or jute fiber obtained by unravelling old ropes;
           when impregnated with tar it was used to caulk seams and
           pack joints in wooden ships