'Voussoir' definitions:

Definition of 'voussoir'

(from WordNet)
noun
Wedge-shaped stone building block used in constructing an arch or vault

Definition of 'Voussoir'

From: GCIDE
  • Voussoir \Vous`soir"\, n. [F., akin to vo[^u]te an arch, a vault.] (Arch.) One of the wedgelike stones of which an arch is composed. [1913 Webster] [1913 Webster]