Definitions

from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun Architecture The central wedge-shaped stone of an arch that locks its parts together.
  • noun The central supporting element of a whole.

from The Century Dictionary.

  • noun The stone of an arch (typically the uppermost stone), which, being the last put in, is regarded as keying or locking the whole structure together; the stone at the apex of an arch.
  • noun Hence A supporting principle; the chief element in a system; that upon which the remainder rests or depends.
  • noun In chromolithography, the first stone on which the picture is drawn or photographed, to serve as an outline guide in preparing the other stones for the colors, a copy of the keystone being made on each stone for printing a single color. See lithography.
  • noun In a Scotch lead-smelting furnace, a block of cast-iron used to close up the space at each end of the forestone, and to fill up the space between the forestone and the back part of the furnace

from the GNU version of the Collaborative International Dictionary of English.

  • noun (Arch.) The central or topmost stone of an arch. This in some styles is made different in size from the other voussoirs, or projects, or is decorated with carving. See Illust. of arch.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun architecture The top stone of an arch.
  • noun A native or resident of the American state of Pennsylvania.

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

  • noun the central building block at the top of an arch or vault
  • noun a central cohesive source of support and stability

Etymologies

Sorry, no etymologies found.

Examples

  • Someone has to hold the arch together while the keystone is put in place, or they are thrown together at a single time improbably falling neatly into place.

    Behe and Theistic Evolution

  • At its simplest, a keystone is a device for harvesting and storing power.

    Tran Siberian

  • Wolves are called keystone predators, because their presence or absence has a radical effect on a whole complex eco-system.

    Elizabeth Cunningham: Howl if You Love Gaia: Cristina Eisenberg's The Wolf's Tooth

  • Along with home ownership, the BA is described as a keystone to the American Dream.

    Coyote Blog » Blog Archive » Comparing College to Home Ownership

  • Plants are also described as keystone mutualists, which provide critical support to pollinators and dispersers.

    Species influences upon ecosystem function

  • The Dell M109S includes a capability called keystone correction, a standard feature in most projectors that adjusts a projected image to give it the proper dimensions, rather than the trapezoidal shape that results when a projector is angled upward.

    Two New Devices Give Presentations Some Portability

  • The more forward thinkers concerned themselves with population viability, not just with small areas versus large ones, and explored the notion of keystone species, meaning those plants and animals that might be especially crucial to maintaining the cohesion of an entire ecological community over time.

    The Song of The Dodo

  • But Pennsylvania's so critical in presidential politics, it's fitting that it be called the keystone state.

    CNN Transcript Oct 17, 2004

  • The more forward thinkers concerned themselves with population viability, not just with small areas versus large ones, and explored the notion of keystone species, meaning those plants and animals that might be especially crucial to maintaining the cohesion of an entire ecological community over time.

    The Song of The Dodo

  • At its simplest, a keystone is a device for harvesting and storing power.

    The Outstretched Shadow

Comments

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  • Central wedge-shaped stone at the top of an arch.

    Also the nickname of Pennsylvania. :)

    August 25, 2008

  • famous for its police force (farce):

    August 25, 2008

  • That would be Mack Sennett's company that's famous for its police force. Not the state of Pennsylvania.

    Just making sure... ;)

    August 25, 2008