Word Study
voussoir
CIDE DICTIONARY
voussoir, n. [F., akin to voûte an arch, a vault.].
One of the wedgelike stones of which an arch is composed. [1913 Webster]
OXFORD DICTIONARY
voussoir, n. each of the wedge-shaped or tapered stones forming an arch.
Etymology
OF vossoir etc. f. pop.L volsorium ult. f. L volvere roll
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