skylight vs fanlight

skylight and fanlight both are nouns.

Word	Noun	Adjective	Verb	Adverb
skylight	Yes	No	No	No
fanlight	Yes	No	No	No

As nouns, skylight and fanlight are synonyms defined as:

skylight (noun)	fanlight (noun)
a window in a roof to admit daylight	a semicircular window over a door or window; usually has sash bars like the ribs of a fan
	a window above a door that is usually hinged to a horizontal crosspiece over the door
	a window in a roof to admit daylight