Origin: Germanic Old English suffix
Fanlight has 4 different meanings across 1 category:
a window above a door that is usually hinged to a horizontal crosspiece over the door
a semicircular window over a door or window; usually has sash bars like the ribs of a fan
a semicircular or semioval window over a door or other window, normally having a fan-like structure of ribs; sometimes hinged to the transom