Noun
a semicircular window over a door or window; usually has sash bars like the ribs of a fan
a window in a roof to admit daylight
a window above a door that is usually hinged to a horizontal crosspiece over the door
Source: WordNetMy rooms were small, not over-clean or well-kept, but from my desk I could look out of my window through the fanlight of Gatti's Music-Hall entrance, across the street, almost on to its stage. Source: Internet
Federal homes had features such as narrow sidelights with an embracing fanlight around the doorway, giant porticoes, gable or flat roofs, and projecting bays on exterior walls. Source: Internet