(Irregular plural: arches).
1. (Architecture) A masonry construction (usually curved) for spanning an opening and supporting the weight above it.
2. A curved bony structure supporting or enclosing organs (especially arches of the feet).
3. A curved shape in the vertical plane that spans an opening.
4. A passageway under an arch; SYN. archway.

(Used of behavior or attitude) Characteristic of those who treat others with condescension; SYN. condescending, patronizing, patronising.
1. Expert in skulduggery.
2. (Of persons) Highest in rank or authority or office; SYN. boss, chief, head, top.

To form an arch; SYN. curve, arc.

1. chief; principal
2. Extreme; most fully embodying the qualities of the kind

1 archaic
2 archery
3 architect; architectural; architecture

(1826-1919) English Radical Member of Parliament and labor unionist, founder of the National Agricultural Union (the first of its kind) 1872.

In masonry, a curved structure that supports the weight of material over an open space, as in a bridge or doorway. The first arches consisted of several wedge-shaped stones supported by their mutual pressure. The term is also applied to any curved structure that is an arch in form only, such as the Arc de Triomphe, Paris, 1806–36.
The Romans are credited with engineering the earliest round keystone arches, used for aqueducts. Other forms of arch include the pointed arch, the corbeled arch of the Maya Indians, the medieval lancet and ogee arches, and the Islamic horseshoe arch.

Natural curved archway created by the coastal erosion of a headland. It is usually formed when the backs of two caves, on either side of the headland, are broken through. The roof of an arch eventually collapses to leave part of the headland isolated as a stack. An example of an arch is Durdle Door in Dorset, England.