ˈōkəm noun
( -s )
Etymology: Middle English okum, from Old English ācumba hurds, tow, literally, off-combings, from ā- (separative and perfective prefix) + -cumba (akin to Old English camb comb) — more at abear , comb
: loosely twisted fiber usually of hemp or jute impregnated with tar or with a tar derivative (as creosote or asphalt) and used in caulking seams (as of the wood hulls and decks of ships) and in packing joints (as of pipes, caissons)