Architrave. The lintel extending from one column or pier to another; also, the lowest of the three main parts of an entablature; also, more loosely, the moulded frame surrounding a door or window (if this frame turns away at the top at right angles, rises vertically, and returns horizontally, forming a shoulder, it is called a shouldered architrave).
-- John Fleming, Hugh Honour & Nikolaus Pevsner, 1991
The Penguin Dictionary of Architecture
Penguin Books, London, England