Webster’s Revised Unabridged Dictionary · 1913
Slub
Slub (slŭb), n. [Etymol. uncertain.] A roll of wool slightly twisted; a rove; — called also slubbing.
Slub, v. t. [imp. & p. p. Slubbed; p. pr. & vb. n. Slubbing.] To draw out and twist slightly; — said of slivers of wool.