coussinets

Noun

coussinet (plural coussinets)

1. A stone placed on the impost of a pier for receiving the first stone of an arch or vault.
   • The intrados of a simple vault is generally formed of the portion of the surface of a cylinder, cylindroid, or sphere, never greater than that of half the solid; and the springing lines of the coussinet, which terminate the walls from which the vault rises, are generally straight lines, parallel to...1830, Sir David Brewster, The Edinburgh Encyclopaedia, page 523
2. Part of the Ionic capital between the abacus and quarter round, which forms the volute.
   • The term balteus is also used by Vitruvius to denote the strap which seems to bind up the coussinet or cushion of the Ionic capital.1842, Joseph Gwilt, An Encyclopædia of Architecture, page 929