The term BED FRAME PART can be summarized as a SLAT, which is a four-letter word. A SLAT is a thin strip of wood or metal used to support a mattress in a bed frame. Slats are usually placed side by side and held together with a frame, allowing the mattress to rest on top. Slats provide support for the mattress and help to keep it from sagging. They also help to distribute weight evenly across the bed frame.