Brick up is a term used when constructing walls, buildings or other structures. It refers to the act of sealing off an opening or cavity with bricks. There are several synonyms for the term, including block off, seal up, close up, wall up, barricade, and obstruct. These synonyms are often used interchangeably with brick up. The choice of synonym may depend on the context within which it is used. For example, one may use the term "barricade" when referring to blocking off a road during construction, while the term "wall up" may be more appropriate for sealing a window or doorway in a building.