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Wedge-shaped stone at the crown of an arch.
Small crushed stone used as filler for the large aggregate in bituminous bound roads.


The central stone or voissoir at the top of the arch, the last part to be put into position to lock the arch in place, often embellished.



in architecture, the stone or brick, usually wedge-shaped, at the top of an arch or vault. Its function is usually accentuated by ornamental patterns and carvings. A decorative keystone often adorns the flat lintel over the apertures of doors or windows. [9–963–l]

keystone, key block

keystone, 1: K
1. The central voussoir of an arch, which is often embellished; until the keystone is in place, no true arch action takes
References in periodicals archive ?
But, according to Keplinger, the ease of the Keystone Country Manor system helped the job go smoothly.
In May 2003, Monatesti met with an ACA, Keystone committee to explain the organizational structure and protocol of the military and the role of the Family Program.
The Keystone Project was the winner of the 1999 National Council of Instructional Administrators "Exemplary Initiative award for classroom learning.
He noted that the new Keystone NA will have less that 0.
However, Wood was not as fortunate; the Fourth Circuit reversed the Tax Court's decision only three weeks after the Keystone decision.
Prior to Keystone and Wood, the Department of Labor had issued an advisory opinion regarding sections 406(a)(1)(A) and 406(c) of the Employee Retirement Income Security Act of 1974, which are basically identical to the Code provisions at issue in Keystone and Wood.
Photo: The nasal bone keystone pattern on theskull of a modern chimp.
Every partner within the Keystone umbrella is an independent agency, individually owned and operated while benefitting from an enhanced array of services and support that comes with being part of the larger group.
The mission of Keystone is to increase the ability of persons with disabilities to adjust to and remain in the community environments of their choice with personal success and satisfaction with as much independence as individually possible.
The Keystone expansion will be the first direct pipeline to connect a growing and reliable supply of Canadian crude oil with the largest refining market in North America," says Hal Kvisle, TransCanada president and CEO.
Here's hoping Keystone and Critical Mass are working on Part 2.