scotia
n. countablen. a deep, curved groove found at the base of a stone column. It creates a dark shadow that helps the base of the building look more interesting.
n. a deep concave moulding, typically found between the two tori of a classical column base. Its profile is usually formed by two arcs of different radii, creating a characteristic shadow line.
The architect added a scotia to the base of the pillars.
By carving a deep scotia into the pedestal, the stonemason created a sharp contrast of light and shadow.
In classical architecture, the scotia serves as a visual transition between the larger convex mouldings of the base, effectively breaking up the verticality of the column with a horizontal band of shadow.
From Latin Scotia (Scotland, lit. "Land of the Scots")
Commonly used in technical descriptions of Attic or Ionic column bases.