The noun day has 10 senses (first 8 from tagged texts)
1. (648) 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. (404) 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")
3. (101) day, daytime, daylight -- (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")
4. (92) day -- (a day assigned to a particular purpose or observance; "Mother's Day")
5. (32) 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. (24) 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. (9) day -- (a period of opportunity; "he deserves his day in court"; "every dog has his day")
8. (2) 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?")
9. 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)
10. Day, Clarence Day, Clarence Shepard Day Jr. -- (United States writer best known for his autobiographical works (1874-1935))