The term 'RIB STRUCTURE' can be solved by the four-letter word 'CAGE'. A rib structure is a type of structural support that is used in many different applications. It is composed of a series of ribs, which are typically made from metal or wood, and are connected together to form a strong and rigid frame. The ribs are usually arranged in a lattice pattern, which provides additional strength and stability. Cages are often used in construction, engineering, and other industries to provide support for structures, such as bridges, buildings, and other large structures.