Apparent Solar Day
From ExoDictionary
Apparent Solar Day
The duration of one rotation of a celestial body on its axis, with respect to the apparent sun. It is measured by successive transits of the apparent sun over the lower branch of a meridian. The length of the apparent solar day on Earth is 24 hours of apparent time and averages the length of the mean solar day, but varies somewhat from day to day.
References
This article is based on NASA's Dictionary of Technical Terms for Aerospace Use
