Cam·ber n.
1. Shipbuilding An upward convexity of a deck or other surface; as, she has a high camber (said of a vessel having an unusual convexity of deck).
2. Arch. An upward concavity in the under side of a beam, girder, or lintel; also, a slight upward concavity in a straight arch. See Hogback.
Camber arch Arch., an arch whose intrados, though apparently straight, has a slightly concave curve upward.
Camber beam Arch., a beam whose under side has a concave curve upward.