1. A small wheel on a swivel, attached under a piece of furniture or other heavy object to make it easier to move: It's a good thing that the sofa had a caster on each of its six legs because it was much easier to move it across the room.
2. Someone who throws something: Byron was a professional caster of nets in the ocean so he could catch fish.

1. The British spelling of "caster" or a swiveling roller fastened under an article of furniture or portable machines to make them movable: A castor on certain segments of furniture facilitate the movement of such structures.
2. An oily odorous secretion of beavers; used in medicine and perfumery: Salvador was surprised to learn that his wife's perfume was made from the unpleasant smelling castor of beavers.

A viscous fixed oil, colorless or pale yellow, extracted from the seeds of the castor-oil plant which is used as a cathartic and lubrication; and also, used in paint and varnish as well as medically: When some people have bowel problems they might take castor oil as a cathartic which causes the emptying of the bowels.