[n] the curved or pointed opening of a support (like the top of a doorway or window)
(architecture) a masonry construction (usually curved) for spanning an opening and supporting the weight above it a passageway under an arch a curved bony structure supporting or enclosing organs (especially arches of the feet) a curved shape in the vertical plane that spans an opening form an arch or curve; "her back arches"; "her hips curve nicely"
A structural form in a building that spans openings by arranging wedge-shaped blocks (voussoirs), such that the pressure exerted by the part of the building above the opening is channeled to the vertical supports of the arch on either side of the opening; there are many varients of the form of the true arch; most common is the semicircular, curved type, but also known are the stilted, segmental, skewed, three centered and flat arch; a false arch can be formed by other means such as corbelling
A curved structure that converts the downward compression force of its own weight, and of any weight pressing down on top of it, into a force along its curve Thhis results in an outward and downward force along the sides and base of the arch
A structural device that supports a vertical load by translating it into axial, inclined forces; a means of spanning an opening by resolving vertical pressure into horizontal or diagonal thrust