packthread

from WordNet (r) 3.0 (2006)

packthread
    n 1: a strong three-ply twine used to sew or tie packages

from 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]