Emily Dickinson Lexicon

OAK'UM, n. [Sax. æcemba, æcumbe, tow. The latter part of the word may be Sax. cemb, a comb.]

The substance of old ropes untwisted and pulled into loose hemp; used for milking the seams of ships, stopping leaks, &c. That formed from untarred ropes is called white oakum.