The term 'chair back' can refer to three different items. The first is a 'splat, ' which is a flat, vertical piece of wood or other material that is attached to the back of a chair. The second is a 'SLAT, ' which is a thin, horizontal piece of wood or other material that is attached to the back of a chair. The third is a 'RECLINER, ' which is a type of chair that can be adjusted to recline at different angles. All three items are commonly used in furniture design and provide support and comfort for the user.