The Collaborative International Dictionary of English v.0.48:
Throwster \Throw"ster\ (thr[=o]"st[~e]r), n. [Throw + -ster.] One who throws or twists silk; a thrower. [1913 Webster]WordNet (r) 3.0 (2006):
throwster n 1: a person who twists silk or rayon filaments into a thread or yarn [syn: throwster, thrower]