Cas″tor (?), n. [L. castor the beaver, Gr. �; of uncertain origin.] 1. (Zoöl.) A genus of rodents, including the beaver. See Beaver.
2. Castoreum. See Castoreum.
3. A hat, esp. one made of beaver fur; a beaver.
I have always been known for the jaunty manner in which I wear my castor.
Sir W. Scott.
4. A heavy quality of broadcloth for overcoats.