Concave

a.	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. As concave . . . as a worm-eaten nut. - Shak.
n.	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.
v. t.	1.	To make hollow or concave. [imp. & p. p. concaved ( ); p. pr. & vb. n. Concaving.]

Adj.

1.

concave - curving inward Antonyms: bulging, convex - curving or bulging outward

arched, arciform, arclike, arcual, bandy, boat-shaped, boatlike, bowed, bowl-shaped, bowlike, bowllike, cavelike, cavernous, concaved, convex, craterlike, cup-shaped, cupped, cymbiform, dish-shaped, dished, dishing, dishlike, embowed, funnel-breasted, funnel-chested, funnel-shaped, gibbose, gibbous, hollow, hollowed, humpbacked, humped, humpy, hunched, hunchy, incurved, incurving, incurvous, infundibular, infundibuliform, navicular, naviform, oxbow, retiring, retreating, saucer-shaped, scaphoid, scyphate, spoonlike, sunk, sunken, vaulted