Day Definition

Define what is Day?

1. 24-hour interval, Day, mean solar day, solar day, twenty-four hour period, twenty-four hours (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.

time unit, unit of time noun
a unit for measuring time periods.


tomorrow noun
the day after today.

today noun
the day that includes the present moment (as opposed to yesterday or tomorrow).

yesterday noun
the day immediately before today.

morrow noun
the next day.

Eve noun
the day before.

date, day of the month noun
the specified day of the month.

date noun
a particular day specified as the time something happens.

2. 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.

time noun
an indefinite period (usually marked by specific attributes or activities).


crack of doom, Last Judgement, Last Day, Judgment Day, Judgement Day, eschaton, end of the world, Doomsday, day of reckoning, Day of Judgment, Day of Judgement, Last Judgment noun
(New Testament) day at the end of time following Armageddon when God will decree the fates of all individual humans according to the good and evil of their earthly lives.

off-day noun
a day when things go poorly.

3. Day (noun)

a day assigned to a particular purpose or observance.

  • Mother's Day.

calendar day, civil day noun
a day reckoned from midnight to midnight.


Admission Day noun
in some states of the United States: a legal holiday commemorating the day the state was admitted to the Union.

Arbor Day noun
a day designated for planting trees.

Cinco de Mayo noun
the fifth of May which is observed in Mexico and Mexican-American communities in the United States to commemorate the Mexican victory over the French in the Battle of Puebla in 1862.

commencement day, degree day noun
the day on which university degrees are conferred.

November 5 noun
anniversary of the discovery of the Gunpowder Plot.

Inauguration Day, January 20 noun
the day designated for inauguration of the United States President.

bissextile day, February 29, leap day noun
the name of the day that is added during a leap year.

V-day, Victory Day noun
the day of a victory.

rag day noun
a day on which university students hold a rag.

red-letter day noun
a memorably happy or noteworthy day (from the custom of marking holy days in red on church calendars).

payday noun
the day on which you receive pay for your work.

election day, polling day noun
the day appointed for an election; in the United States it is the 1st Tuesday after the 1st Monday in November.

field day noun
a day for outdoor athletic competition.

field day noun
(military) a day for military exercises and display.

ides noun
in the Roman calendar: the 15th of March or May or July or October or the 13th of any other month.

market day noun
a fixed day for holding a public market.

Walpurgis Night noun
eve of May Day.

December 31, New Year's Eve noun
the last day of the year.

January 19, Lee's Birthday, Robert E Lee's Birthday, Robert E Lee Day noun
celebrated in southern United States.

Tet noun
the New Year in Vietnam; observed for three days after the first full moon after January 20th.

holiday noun
a day on which work is suspended by law or custom.

February 2, Groundhog Day noun
if the ground hog emerges and sees his shadow on this day, there will be 6 more weeks of winter.

February 12, Lincoln's Birthday noun
the day on which President Abraham Lincoln is remembered.

February 14, Saint Valentine's Day, St Valentine's Day, Valentine's Day, Valentine Day noun
a day for the exchange of tokens of affection.

February 22, Washington's Birthday noun
the day on which George Washington is remembered.

March 2, Texas Independence Day noun
Texans celebrate the anniversary of Texas' declaration of independence from Mexico in 1836.

March 17, Saint Patrick's Day, St Patrick's Day noun
a day observed by the Irish to commemorate the patron saint of Ireland.

All Fools' day, April Fools', April Fools' day noun
the first day of April which is celebrated by playing practical jokes.

April 14, Pan American Day noun
a day celebrating political and economic unity among American countries.

Patriot's Day noun
the 3rd Monday in April; Massachusetts and Maine celebrate the battle of Lexington and Concord in 1775.

First of May, May 1, May Day noun
observed in many countries to celebrate the coming of spring; observed in Russia and related countries in honor of labor.

Mother's Day noun
second Sunday in May.

Armed Forces Day noun
the 3rd Saturday in May.

Davis' Birthday, Jefferson Davis' Birthday, June 3 noun
celebrated in southern United States.

Flag Day, June 14 noun
commemorating the adoption of the United States flag in 1777.

Father's Day noun
US: third Sunday in June.

Citizenship Day, September 17 noun
celebrated in the United States.

American Indian Day noun
US: the 4th Friday in September.

October 24, United Nations Day noun
a day for celebrating the founding of the United Nations.

Allhallows Eve, Hallowe'en, Halloween noun
the evening before All Saints' Day; often devoted to pranks played by young people.

saint's day noun
a day commemorating a saint.

June 23, Midsummer Eve, Midsummer Night, St John's Eve, St John's Night noun
the night before Midsummer Day.

school day noun
any day on which school is in session.

speech day noun
an annual day in the schools when speeches are made and prizes are distributed.

washday, washing day noun
a day set aside for doing household laundry.

wedding day noun
the day of a wedding.

anniversary, day of remembrance noun
the date on which an event occurred in some previous year (or the celebration of it).

4. daylight, daytime, Day (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.
Synonyms: daylight, daytime
Antonyms: Night, nighttime, dark (noun)

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


period, period of time, time period noun
an amount of time.


afternoon noun
the part of the day between noon and evening.

midafternoon noun
the middle part of the afternoon.

even, evening, eventide, Eve noun
the latter part of the day (the period of decreasing daylight from late afternoon until nightfall).

5. 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.

work time noun
a time period when you are required to work.


workday, working day noun
the amount of time that a worker must work for an agreed daily wage.

6. 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.

epoch, ERA noun
a period marked by distinctive character or reckoned from a fixed point or event.

7. 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?.

period, period of time, time period noun
an amount of time.


lunar day noun
the period of time taken for the moon to make one full rotation on its axis (about 27.3 sidereal days).

8. 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.

    Synonyms: sidereal day

    time unit, unit of time noun
    a unit for measuring time periods.

    sidereal time noun
    measured by the diurnal motion of stars.

    9. Day (noun)

    a period of opportunity.

    • he deserves his day in court.
    • every dog has his day.

    chance, opportunity noun
    a possibility due to a favorable combination of circumstances.

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

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

      Nearby Terms

      day after day (adverb)
      for an indefinite number of successive days

      day bed (noun)
      convertible consisting of an upholstered couch that can be converted into a double bed

      day blindness (noun)
      inability to see clearly in bright light

      day boarder (noun)
      a schoolchild at a boarding school who has meals at school but sleeps at home

      day book (noun)
      the daily written record of events (as arrests) in a police station

      day by day (adverb)
      gradually and progressively

      day camp (noun)
      a camp providing care and activities for children during the daytime

      day care (noun)
      childcare during the day while parents work

      day care center (noun)
      a nursery for the supervision of preschool children while the parents work

      day game (noun)
      a game played in daylight

      day in and day out (adverb)
      without respite

      day in day out (adverb)
      for an indefinite number of successive days

      day jessamine (noun)
      West Indian evergreen shrub having clusters of funnel-shaped white flowers that are fragrant by day

      day laborer (noun)
      a laborer who works by the day; for daily wages

      day labourer (noun)
      a laborer who works by the day; for daily wages