1. a small wheel or roller attached to the bottom of furniture to make it movable
2. a container with holes in the top for sprinkling salt, sugar, or other substances
3. a large semiaquatic rodent with webbed feet and a flat tail, valued for its fur
Usage: zoology

Examples

• The office chair rolled smoothly on its castors.
• She moved the heavy desk by pushing it on its castors.
• Pass me the sugar castor, please.
• The salt castor was nearly empty.
• Castors build dams across streams and rivers.
• Castor oil is used as a laxative.
• The castor plant produces toxic seeds.