from The American Heritage® Dictionary of the English Language, 4th Edition

  • adj. Curved like the inner surface of a sphere.
  • n. A concave surface, structure, or line.
  • transitive v. To make concave.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • adj. curved like the inner surface of a sphere or bowl
  • n. A concave surface or curve.
  • n. The vault of the sky.
  • n. One of the celestial spheres of the Ptolemaic or geocentric model of the world.
  • n. An element of a curved grid used to separate desirable material from tailings or chaff in mining and harvesting.
  • n. An indentation running along the base of a surfboard, intended to increase lift.
  • n. An indented area on the top of a skateboard, providing a position for foot placement and increasing board strength.
  • v. To render concave, or increase the degree of concavity.

from the GNU version of the Collaborative International Dictionary of English

  • adj. 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.
  • adj. Hollow; void of contents.
  • n. A hollow; an arched vault; a cavity; a recess.
  • n. A curved sheath or breasting for a revolving cylinder or roll.
  • transitive v. To make hollow or concave.

from The Century Dictionary and Cyclopedia

  • Curved or rounded in the manner of the circumference of a circle or the surface of a sphere when viewed from the center; presenting a hollow or incurvation; incurved; hence, bounded by such a line or surface: as, a concave mirror.
  • Hollow; empty.
  • n. A hollow; an arch or vault; a concavity.
  • n. Any inwardly curved portion of a machine: as, the concave of a thresher (the curved breast in which the cylinder works).
  • n. A concave mirror.
  • To make hollow.
  • n. The vault or arch of heaven: as, “the blue concave.”
  • n. A playing card so trimmed that it can be separated from others according to the purpose for which the pack was prepared.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • adj. curving inward


from The American Heritage® Dictionary of the English Language, 4th Edition

Middle English, from Latin concavus : com-, intensive pref.; see com- + cavus, hollow.

from Wiktionary, Creative Commons Attribution/Share-Alike License

From Latin concavus.


  • It flowed in a gentle concave from the road up the mountain, its farther boundary an unbroken line of timber.

    Chapter 17

  • The last three types, called concave lenses, scatter parallel rays so that they do not come to a focus, but diverge widely after passage through the lens.

    General Science

  • That surface of the bow which faces the string when drawn into action, that is, the concave arc, is called the belly of the bow.

    Hunting with the Bow and Arrow

  • It rises in a concave, which is glazed in the same manner as that I described in the house, and like that, defended on the outside from the pecking of birds by a wire net; with the difference, of its being painted green.

    Vicissitudes in Genteel Life

  • The concave is a little mellower than I prefer riding, but it ran full length so forwards or backwards it still felt like it wanted to stick to my feet (thankfully!).

    Caught in the Crossfire - Articles

  • Two other celestial bodies of the feminine gender, fixed for one brief week apiece on the theatrical "concave," moved quickly in the direction of "the road."

    Ainslee's, Vol. 15, No. 5, June 1905

  • Some had a kind of concave, cylindrical, stiff black cap, which appeared to be a great ornament among them, and, we thought, was only worn by men of note or warriors.

    A General History and Collection of Voyages and Travels — Volume 14

  • Round the sides and ends of the huts, the families, (for several are lodged together) have their separate apartments, where they sleep, and sit at work, not upon benches, but in a kind of concave trench, which is dug all round the inside of the house, and covered with mats; so that this part is kept tolerably decent.

    A General History and Collection of Voyages and Travels, Volume 16

  • This "concave" image is from the roof of the mosque next to the Taj Mahal in Agra. 50mm, wide open at f/1.4.

    WordPress Planet

  • Every cranny and crater and concave void in her being was transformed from parched to pulsing.

    Amaryllis in Blueberry


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