day

The word “day” means the 24-hour period during which the Earth completes one rotation, from one midnight to the next. In plain terms, one rotation of the Earth (24 hours), the light part of that period, or — loosely — an era or time in history.

“Day” is pronounced DAY (/ˈdeɪ̯/ in IPA).

Here is “day” used in a sentence: “We spent three days hiking through the mountains.”

Words with a similar meaning to “day” include yearday.

“Day” is a noun.

The word “day” comes from Old English. From Old English dæg, an ancient Germanic word ultimately traced back to a Proto-Indo-European root meaning "to burn" — likely a reference to the heat and light of the sun.

“Day” is a very common word in modern English, usually learned at around the A1 level.

“Day” has 4 distinct senses listed in this dictionary. The most common is: the 24-hour period during which the Earth completes one rotation, from one midnight to the next.

A day in this sense is the full 24-hour period from one midnight to the next, covering both light and dark. Daytime is only the lit part, from sunrise to sunset. So a winter day is still 24 hours long even when its daytime — the hours of daylight — is short.

A day is the time the Earth takes to spin once on its axis, and that rotation lasts roughly 24 hours. As the planet turns, each place moves from midnight through morning, noon, and evening back to midnight — one full turn, one full day. We divide that span into 24 equal hours.

The everyday calendar day runs midnight to midnight. Astronomers also use the solar day (noon to noon, the basis of our 24 hours) and the sidereal day (one rotation measured against the stars, about four minutes shorter). 'Day' can also mean just the daylight hours, depending on context.