\Con"cave\ (k[o^][ng]*k[=a]*v" or k[o^]n"-; 277), 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.
2. Hollow; void of contents. [R.]
         As concave . . . as a worm-eaten nut. --Shak.

\Con"cave\, n. [L. concavum.]
1. A hollow; an arched vault; a cavity; a recess.
         Up to the fiery concave towering hight. --Milton.
2. (Mech.) A curved sheath or breasting for a revolving
   cylinder or roll.

\Con"cave\, v. t. [imp. & p. p. {concaved}; p. pr. & vb.
n. {Concaving}.]
To make hollow or concave.