What does "arch" mean?

Arch: (Arch.) (a) Usually a curved member made up of separate wedge-shaped solids, with the joints between them disposed in the direction of the radii of the curve; used to support the wall or other weight above an opening. In this sense arches are segmental, round (i. e., semicircular), or pointed. (b) A flat arch is a member constructed of stones cut into wedges or other shapes so as to support each other without rising in a curve. Note: Scientifically considered, the arch is a means of spanning an opening by resolving vertical pressure into horizontal or diagonal thrust.

Additional senses

  1. 2.Any place covered by an arch; an archway; as, to pass into the arch of a bridge.
  2. 3.Any curvature in the form of an arch; as, the arch of the aorta. "Colors of the showery arch." Milton. Triumphal arch, a monumental structure resembling an arched gateway, with one or more passages, erected to commemorate a triumph.
  3. 4.To cover with an arch or arches.
  4. 5.To form or bend into the shape of an arch. The horse arched his neck. Charlesworth.
  5. 6.To form into an arch; to curve.
  6. 7.Chief; eminent; greatest; principal. The most arch act of piteous massacre. Shak.
  7. 8.Cunning or sly; sportively mischievous; roguish; as, an arch look, word, lad. [He] spoke his request with so arch a leer. Tatler.
  8. 9.A chief. [Obs.] My worthy arch and patron comes to-night. Shak.
  9. 10.A suffix meaning a ruler, as in monarch (a sole ruler).

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