ETYM Old Eng. day, dai, dei, as. daeg; akin to os., Dutch, Dan., and Swed. dag, G, tag, Icel. dagr, Goth. dags; cf. Skr. dah (for dhagh ?) to burn. Related to Dawn.
1. Time for Earth to make a complete rotation on its axis; twenty-four hours; SYN. twenty-four hours, solar day, mean solar day.
2. The time after sunrise and before sunset while it is light outside; SYN. daytime, daylight.
3. The recurring hours established by contract or usage for work.
4. The period of time taken by a particular planet (e.g. Mars) to make a complete rotation on its axis.
5. A day assigned to a particular purpose or observance.
6. Some point or period in time.
7. An era of existence or influence.
8. A period of opportunity.
Time taken for the Earth to rotate once on its axis. The solar day is the time that the Earth takes to rotate once relative to the Sun. It is divided into 24 hours, and is the basis of our civil day. The sidereal day is the time that the Earth takes to rotate once relative to the stars. It is 3 minutes 56 seconds shorter than the solar day, because the Sun’s position against the background of stars as seen from Earth changes as the Earth orbits it.