Definition of "day"
Any period of 24 hours.
A period from midnight to the following midnight.
Rotational period of a planet (especially earth).
The part of a day period which one spends at one's job, school, etc.
Part of a day period between sunrise and sunset where one enjoys daylight; daytime.
A specified time or period; time, considered with reference to the existence or prominence of a person or thing; age; time.
A period of contention of a day or less.
To spend a day (in a place).