/nub/ , n.
1. the point, gist, or heart of something.
2. a knob or protuberance.
3. a lump or small piece: a nub of coal; a nub of pencil.
4. a small mass of fibers produced on a card, dyed brilliant colors, and introduced into yarn during the spinning process.
Also, knub .
[ 1585-95; knubbe; cf. KNOB ]