The crossword solution for the term 'board in a wall' is STUD, which is a four-letter word. A STUD is a vertical framing member used in the construction of walls. It is typically made of wood, metal, or plastic and is used to support the weight of the wall and to provide a nailing surface for the wall covering. Studs are usually spaced 16 inches apart and are used to create a strong, durable wall structure.