night vs day

night and day both are nouns.

Word	Noun	Adjective	Verb	Adverb
night	Yes	No	No	No
day	Yes	No	No	No

night (noun)	day (noun)
darkness	a period of opportunity
the time after sunset and before sunrise while it is dark outside	time for Earth to make a complete rotation on its axis
a period of ignorance or backwardness or gloom	a day assigned to a particular purpose or observance
the dark part of the diurnal cycle considered a time unit	the time after sunrise and before sunset while it is light outside
the time between sunset and midnight	a point or period in time
the period spent sleeping	the recurring hours when you are not sleeping (especially those when you are working)
a shortening of nightfall	an era of existence or influence
	the time for one complete rotation of the earth relative to a particular star, about 4 minutes shorter than a mean solar day
	the period of time taken by a particular planet (e.g. Mars) to make a complete rotation on its axis