Caster (noun)

1. A small wheel or ball mounted in a socket or housing, enabling an object to be moved easily.
2. A device that allows an object to be rolled around.
3. A small wheel or rollers that are attached to the bottom of a piece of furniture to make it easier to move.

Origin:

Early 17th century: from french casseur, from casser "to break", from latin quassare.

Examples:

1. The chair had casters on the bottom so it could be easily moved around.
2. The table had casters on the legs so it could be easily moved.
3. The casters on the bottom of the cart make it easy to move it around.
4. The casters are used to move the heavy equipment around.
5. The casters on the bottom of the piano made it easy to move it to a different room.