cantilever, beam supported rigidly at one end to carry a load along the free arm or at the free end. A slanting beam fixed at the base is often used to support the free end, as in a common bracket. The springboard is a simple cantilever beam, and the cantilever design is often used for canopies, balconies, sidewalks outside the trusses of bridges, and large cranes such as those used in shipyards. By the use of cantilever trusses, obstructing columns are eliminated in theaters. The cantilever principle is one of the methods that may be used in constructing a bridge.

Projecting beam or other horizontal member supported at one or more points but not at both ends. Some engineers distinguish between a cantilever, supported at only one fixed end, and an overhanging beam that projects beyond one of its end supports. The free, unsupported end is capable of supporting a weight or surface, such as a concrete slab. Any beam built into a wall with a projecting free end forms a cantilever, which may carry a balcony, canopy, roof, or part of a building above. Cantilevering can be used for constructions as simple as bookshelves or as complicated as bridges.

Learn more about cantilever with a free trial on Britannica.com.