taps vs lights-out

taps and lights-out both are nouns.

Word	Noun	Adjective	Verb	Adverb
taps	Yes	No	No	No
lights-out	Yes	No	No	No

As nouns, taps and lights-out are synonyms defined as:

taps (noun)	lights-out (noun)
(military) signal to turn the lights out	(military) signal to turn the lights out
	a prescribed bedtime