concave

comparative more concave · superlative most concave

1. Curved like the inner surface of a sphere or bowl.
2. not comparablegeometryNot convex; having at least one internal angle greater than 180 degrees.
3. not comparablefunctional analysisSatisfying the property that all segments connecting two points on the function's graph lie below the function.
4. Hollow; empty.

   as concave […] as a worm-eaten nut

   c. 1598–1600 (date written), William Shakespeare, “As You Like It”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, →OCLC, [Act III, scene iv]

plural concaves

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.

   Aristotle makes [Fire] to move to the concave of the Moon. - Thomas Salusbury (1661).

4. businessAn element of a curved grid used to separate desirable material from tailings or chaff in mining and harvesting.
5. hobbiesAn indentation running along the base of a surfboard, intended to increase lift.
6. hobbiesAn indented area on the top of a skateboard, providing a position for foot placement and increasing board strength.
7. gamblingA playing card made concave for use in cheating.

present singular third person concaves · participle present concaving · participle past concaved · past concaved

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