concave

a. [ L. concavus; con- + cavus hollow: cf. F. concave. See Cave a hollow. ] 1. Hollow and curved or rounded; vaulted; -- said of the interior of a curved surface or line, as of the curve of the of the inner surface of an eggshell, in opposition to convex; as, a concave mirror; the concave arch of the sky. [ 1913 Webster ]

2. Hollow; void of contents. [ R. ] [ 1913 Webster ]

As concave . . . as a worm-eaten nut. Shak. [ 1913 Webster ]

n. [ L. concavum. ] 1. A hollow; an arched vault; a cavity; a recess. [ 1913 Webster ]

Up to the fiery concave towering hight. Milton. [ 1913 Webster ]

2. (Mech.) A curved sheath or breasting for a revolving cylinder or roll. [ 1913 Webster ]

v. t. [ imp. & p. p. concaved p. pr. & vb. n. Concaving. ] To make hollow or concave. [ 1913 Webster ]

a. (Her.) Bowed in the form of an arch; -- called also arched. [ 1913 Webster ]