Board up is a term used to describe the process of covering and securing a structure, such as a window or door, with a board. This is often done to prevent access to the structure, or to protect it from damage. Board up is commonly used in construction, renovation, and emergency situations. It is also used to protect structures from natural disasters, such as hurricanes and floods. The two crossword solutions for the term board up are COVER (5 letters) and SECURE (6 letters).