(1):
(a.) Hollow; void of contents.
(2):
(v. t.) To make hollow or concave.
(3):
(n.) A curved sheath or breasting for a revolving cylinder or roll.
(4):
(n.) A hollow; an arched vault; a cavity; a recess.
(5):
(a.) 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.