Castor/ˈkæstər/ Definition 1 of 4Pro Tip 1/2Mobility Enhancement Used to describe wheels that help move heavy objects effortlessly. The bedside table's castors made redecorating the room a breeze. Pro Tip 2/2Furniture Specific Most commonly associated with movable pieces of furniture or heavy appliances. I added castors to the bookshelf to make it easier to clean around it.