concave - Wiktionary, the free dictionary (original) (raw)

Top: a spoon with its convex side up.
Bottom: a spoon with its concave side up.

A concave polygon.

A concave (concave downwards) function.

From Middle English concave, from Old French concave, from Latin concavus.

concave (comparative more concave, superlative most concave)

  1. Curved like the inner surface of a sphere or bowl.
  2. (geometry, not comparable, of a polygon) Not convex; having at least one internal angle greater than 180 degrees.
  3. (functional analysis, not comparable, of a real-valued function on the reals) Satisfying the property that all segments connecting two points on the function's graph lie below the function.
  4. Hollow; empty.

curved inward

concave (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. (manufacturing) An element of a curved grid used to separate desirable material from tailings or chaff in mining and harvesting.
  5. (surfing) An indentation running along the base of a surfboard, intended to increase lift.
  6. (skateboarding) An indented area on the top of a skateboard, providing a position for foot placement and increasing board strength.
  7. (gambling) A playing card made concave for use in cheating.
    Coordinate term: convex

concave (third-person singular simple present concaves, present participle concaving, simple past and past participle concaved)

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

To render concave, or increase the degree of concavity.

Inherited from Old French concave, borrowed from Latin concavus.

concave (plural concaves)

  1. concave

concave

  1. feminine plural of concavo

concave

  1. vocative masculine singular of concavus