Meaning

noun the time after sunset and before sunrise while it is dark outside

noun a period of ignorance or backwardness or gloom

noun the period spent sleeping

originInherited from Middle English nightes, from Old English nihtes (“at night, by night”), equivalent to night + -s (adverbial genitive suffix). Cognate with Old Frisian nachtes, Old Saxon nahtes, German nachts (all “nights, at night”).

Etymology from Wiktionary, CC BY-SA 3.0