night

(countable) The period between sunset and sunrise, when a location faces far away from the sun, thus when the sky is dark.

(astronomy, countable) The period of darkness beginning at the end of evening astronomical twilight when the sun is 18 degrees below the horizon, and ending at the beginning of morning astronomical twilight.

(law, countable) A period of time often defined in the legal system as beginning 30 minutes after sunset, and ending 30 minutes before sunrise.

(countable) An evening or night spent at a particular activity.

(countable) A night (and part of the days before and after it) spent in a place away from home, e.g. a hotel.

(uncountable) Nightfall.

(uncountable) Darkness (due to it being nighttime).

(uncountable) A dark blue colour, midnight blue.

(sports, colloquial) A night's worth of competitions, generally one game.