From AMS Glossary
- (Also called tidal day.) The time required for the earth to rotate once with respect to the moon, that is, the time between two successive upper transits of the moon.
The mean lunar day is approximately 1.035 times as great as the mean solar day, or 24 hours 50 minutes.
- In astronomy, the time required for the moon to revolve once, relative to a fixed star, about its own axis.