1. (noun)day, twenty-four hours, twenty-four hour period, 24-hour interval, solar day, mean solar day 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"
2. (noun)day 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"
4. (noun)day, daytime, daylight the time after sunrise and before sunsetwhile it is lightoutside "the dawn turned night into day"; "it is easier to make the repairs in the daytime"
5. (noun)day 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"
6. (noun)day 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"
7. (noun)day 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?"
8. (noun)sidereal day, day the time for one complete rotation of the earth relative to a particular star, about 4 minutes shorter than a mean solar day
9. (noun)day a period of opportunity
"he deserves his day in court"; "every dog has his day"
10. (noun)Day, Clarence Day, Clarence Shepard Day Jr. United States writer best known for his autobiographical works (1874-1935)