The Collaborative International Dictionary of English v.0.48:
packthread \packthread\, pack thread \pack thread\n. A strong three-ply thread or small twine used to sew or tie packs or packages. [WordNet 1.5]The Collaborative International Dictionary of English v.0.48:
Pack saddle \Pack saddle\, Pack thread \Pack thread\ See under 2d Pack. [1913 Webster] packthread