oakum Look up oakum at Dictionary.com
"loose fiber obtained from taking apart old hemp ropes," 1420s, from O.E. acumba "tow, oakum, flax fibers separated by combing," lit. "what is combed out," from a- "away, out, off" + stem of cemban "to comb," from camb "a comb;" from P.Gmc. *us-kambon, second element from PIE *gembh- "tooth, nail" (see comb).