Noun
Palladian window (plural Palladian windows)
A window consisting of a central light with a semicircular arch over it, carried on an impost consisting of a small entablature, under which, and enclosing two other lights, one on each side, are pilasters.
In the original house, the high corner pavilion blocks of Inigo Jones ' Wilton were provided with the " Palladian window " motif to be seen at Burlington House. Source: Internet