day, twenty-four hours, twenty-four hour period, 24-hour interval, solar day, mean solar day (noun)

time for Earth to make a complete rotation on its axis

"two days later they left"; "they put on two performances every day"; "there are 30,000 passengers per day"

day (noun)

some point or period in time

"it should arrive any day now"; "after that day she never trusted him again"; "those were the days"; "these days it is not unusual"

day (noun)

a day assigned to a particular purpose or observance

"Mother's Day"

day, daytime, daylight (noun)

the time after sunrise and before sunset while it is light outside

"the dawn turned night into day"; "it is easier to make the repairs in the daytime"

day (noun)

the recurring hours when you are not sleeping (especially those when you are working)

"my day began early this morning"; "it was a busy day on the stock exchange"; "she called it a day and went to bed"

day (noun)

an era of existence or influence

"in the day of the dinosaurs"; "in the days of the Roman Empire"; "in the days of sailing ships"; "he was a successful pianist in his day"

day (noun)

the period of time taken by a particular planet (e.g. Mars) to make a complete rotation on its axis

"how long is a day on Jupiter?"

sidereal day, day (noun)

the time for one complete rotation of the earth relative to a particular star, about 4 minutes shorter than a mean solar day

day (noun)

a period of opportunity

"he deserves his day in court"; "every dog has his day"

Day, Clarence Day, Clarence Shepard Day Jr. (noun)

United States writer best known for his autobiographical works (1874-1935)

day (Noun)

Any period of 24 hours.

day (Noun)

A period from midnight to the following midnight.

day (Noun)

Rotational period of a planet (especially earth).

day (Noun)

The part of a day period which one spends at one's job, school, etc.

day (Noun)

Part of a day period between sunrise and sunset where one enjoys daylight, daytime.

day (Noun)

A specified time or period; time, considered with reference to the existence or prominence of a person or thing; age; time.

day (Noun)

A period of contention of a day or less.

day (Verb)

To spend a day (in a place).

Day (ProperNoun)

A Mbum-Day language of Chad.

Day

A day is a unit of time. In common usage, it is an interval equal to 24 hours. It also can mean the consecutive period of time during which the Sun is above the horizon of a location, also known as daytime. The period of time measured from local noon to the following local noon is called a solar day. Several definitions of this universal human concept are used according to context, need and convenience. In 1967, the second was redefined in terms of the wavelength of light, and it became the SI base unit of time. The unit of measurement for time called "day", redefined in 1967 as 86,400 SI seconds and symbolized d, is not an SI unit, but it is accepted for use with SI. A civil day is usually also 86,400 seconds, plus or minus a possible leap second in Coordinated Universal Time UTC, and, in some locations, occasionally plus or minus an hour when changing from or to daylight saving time. The word day may also refer to a day of the week or to a calendar date, as in answer to the question "On which day?" Day also refers to the part of the day that is not night — also known as daytime. The life patterns of humans and many other species are related to Earth's solar day and the cycle of day and night.