from the Merriam-Webster Collegiate Dictionary oa*kum (noun) [Middle English okum, from Old English acumba tow, from a- (separative & perfective prefix) + -cumba (akin to Old English camb comb) -- more at ABIDE] First appeared 15th Century : loosely twisted hemp or jute fiber impregnated with tar or a tar derivative and used in caulking seams and packing joints