Concave

Adjective

 * 1) curved like the inner surface of a sphere or bowl

Antonyms

 * convex

Noun

 * 1) A concave surface or curve.
 * 2) The vault of the sky.
 * 3) One of the celestial spheres of the Ptolemaic or geocentric model of the world.
 * 4)  An element of a curved grid used to separate desirable material from tailings or chaff in mining and harvesting.
 * 5)  An indentation running along the base of a surfboard, intended to increase lift.
 * 6)  An indented area on the top of a skateboard, providing a position for foot placement and increasing board strength.

Verb

 * 1) To render concave, or increase the degree of concavity.

Thesaurus
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

Derived terms

 * concavely
 * concaveness
 * concavity