thrum 2 
(thrŭm)
(thrŭm)n.
1.
a. The fringe of warp threads left on a loom after the cloth has been cut off.
b. One of these threads.
2. A loose end, fringe, or tuft of thread or wool.
tr.v. thrummed, thrum·ming, thrums
1. To cover or trim with thrums; fringe.
2. To knit thrums into (mittens, hats, or socks).
[Middle English, from Old English -thrum, ligament (in tungethrum, ligament of the tongue).]