from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Architecture The central wedge-shaped stone of an arch that locks its parts together. Also called headstone.
- n. The central supporting element of a whole.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. The top stone of an arch.
- n. A native or resident of the American state of Pennsylvania.
from the GNU version of the Collaborative International Dictionary of English
- n. 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 The Century Dictionary and Cyclopedia
- n. 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.
- n. Hence A supporting principle; the chief element in a system; that upon which the remainder rests or depends.
- n. 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.
- n. 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 WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. the central building block at the top of an arch or vault
- n. a central cohesive source of support and stability
Sorry, no etymologies found.
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.
Wolves are called keystone predators, because their presence or absence has a radical effect on a whole complex eco-system.
Along with home ownership, the BA is described as a keystone to the American Dream.
Plants are also described as keystone mutualists, which provide critical support to pollinators and dispersers.
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.
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.
But Pennsylvania's so critical in presidential politics, it's fitting that it be called the keystone state.
At its simplest, a keystone is a device for harvesting and storing power.
Probation is of such importance that it has been termed the keystone of the juvenile court system.
Carved on each side of the niche above the keystone is a