Look up: Voussoirs

1. voussoirs
   the wedge-shaped stones that form the curve of an arch
   Found on http://www.encyclo.co.uk/local/20559
   
   
2. voussoirs
   (Learning Modules / Mathematics / Bridges) The trapezoidal stones that are often used to form a rounded arch. The central voussoir is known as the 'keystone' and begins the distribution of the vertical 'load' forces down and around the arch. The keystone is the last voussoir to be placed in position, and allows each half of the arch to support the other.
   Found on http://www.encyclo.co.uk/visitor-contrib
   
   
3. Voussoirs
   The wedge-shaped stones that form the curved portions of an arch or a vaulted ceiling. Also see: arch, archivolt, keystone, springer. W
   Found on http://www.virtualani.org/glossary/index
   
   
4. voussoirs
   stones or bricks used in the construction of an arch. Usually wedge shaped
   Found on http://www.castles-of-britain.com/glossa