The crossword solutions for the term RIGID STRUCTURE; FIT UP are FRAME (5 letters). A FRAME is a rigid structure that is used to support or enclose something. It is usually made of wood, metal, or other materials and is designed to fit together in a specific way. Frames are commonly used in construction, engineering, and architecture to provide support for buildings, bridges, and other structures. They can also be used to create furniture, artwork, and other decorative items.