voussoir

[1728] Borrowed from French voussoir, from Old French vosoir, from Vulgar Latin *volsorium, from *volsus, from Latin volvō (“I roll”).

voussoir (plural voussoirs)

1. (architecture) One of a series of wedge-shaped bricks or stones forming an arch or vault.
   • 1977, Jaques Heyman, Equilibrium of Shell Structures, Clarendon Press, Oxford, page 2:

     It is the voussoir depth in a real arch which enables the arch to carry wider ranges of loading; a large number of different idealized centre-line arches can be contained within a given practical profile. ...[T]his must be so, or no mediaeval bridge would have survived its decentering.

• voussoired