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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 ?
Adding Devin to our executive leadership team is a great reflection of both the current momentum Keystone has as well as our commitment to building an exceptional talent base for the future," said Ravndal.
Once completed, Keystone will be operated as one integrated pipeline system which will include the proposed Keystone XL pipeline project.
Keystone operates 135 distribution facilities in 38 states and Canada, employing about 3,700.
He took the idea to Bob Miner, ACA Keystone Regional president, and Michael Chauveau, executive director of ACA, Keystone Regional.
Information: Keystone Symposia, 221 Summit Place #272, Drawer 1630, Silverthorne, CO 80498 USA, 800-253-0685, fax: 970-262-1525, e-mail: info@keystonesymposia.
Keystone Property Trust announces construction is on schedule at the company's Greenville Yards development in Jersey City, N.
will broaden its Keystone brand family with three new brands, the company has announced.
Facts: Keystone maintained several defined benefit plans over the period 1983-1988 and met its funding obligation by making contributions to a pension trust.
Basic questions regarding these rules, however, remained unresolved until the Supreme Court's decision in Keystone Consolidated Industries.
Eckhardt of Pennsylvania State University in University Park, the paranthropine keystone pattern occurs on about 8 percent of modern ape skulls.
LAS VEGAS -- Keystone Solutions, the industry's most experienced full-service digital measurement group, is proud to announce the addition of Hila Strong to the Keystone Solutions Management team.
University of Pennsylvania inquiry of Keystone STARS serves as springboard for stakeholder engagement with program reform.