oakum
oa.kum \'o--k*m\ n [ME okum, fr. OE a-cumba tow, fr. a-- (separative & per]fective prefix) + -cumba (akin to OE camb comb) - more at ABIDE : loosely twisted hemp or jute fiber impregnated with tar or a tar derivat ive and used in caulking seams and packing joints