Slub

n.	1.	A roll of wool slightly twisted; a rove; - called also slubbing.
v. t.	1.	To draw out and twist slightly; - said of slivers of wool. [imp. & p. p. Slubbed ; p. pr. & vb. n. Slubbing.]

Noun

1.

slub - soft lump or unevenness in a yarn; either an imperfection or created by design Synonyms: burl, knot

burl, knot, roughness