Corona

Chambers's Encyclopaedia, Volume 3: Catarrh to Dion, p. 491

Corona (Lat., 'a crown'), in Architecture, the drip, or lower member of the projecting or upper part of a classical cornice (see ENTABLATURE). The term corona is also applied to the apse or semicircular termination of the choir. Corona is also applied in ecclesiastical nomenclature to a chandelier, in the form of a crown or circlet, suspended from the roof of a church.

A technical drawing of a classical architectural cornice. It shows a horizontal band with a series of horizontal lines representing the layers of the cornice. Below this band, a small letter 'a' is positioned, indicating the corona, which is the lowermost part of the cornice.
a, the Corona.
Source scan(s): p. 0502