mean time

noun

1. the time, at a particular place, measured in terms of the passage of the mean sun; the timescale is not precisely constant See mean solar day

mean time

1. Solar time as measured by the mean sun, resulting in equal 24-hour days throughout the year. If days were measured by the actual movement of the Sun, they would vary slightly in length at different times of the year due to differences in Earth's orbital speed and other factors. Mean time is the basis for standard clock time throughout most of the world.

2. See more at solar time universal time