1. a person or thing that casts.
2. a small wheel on a swivel, set under a piece of furniture, a machine, etc., to facilitate moving it.
3. a bottle or cruet for holding a condiment.
4. a stand for such bottles.
5. a container for sugar, pepper, etc., having a perforated top.
6. the angle that a car's kingpin makes with the vertical.
Also, castor (for defs. 2–5).