The crossword solution for the term 'STOP UP, IN A WAY' is CAULK, which is a five-letter word. Caulking is a process of sealing cracks or gaps in various materials, such as wood, metal, and stone. It is often used to prevent water from entering a structure, and can also be used to fill in gaps between two surfaces. Caulking is typically done with a sealant, such as silicone, latex, or polyurethane.