The time of the rotation of the Earth with respect to the Moon, or the interval between two successive upper transits of the Moon over the meridian of a place. The mean lunar day is approximately 24.84 solar hours in length, or 1.035 times as great as the mean solar day.

the period of time taken for the moon to make one full rotation on its axis (about 27.3 sidereal days)

(or tidal day). The interval between two successive upper transit s of the moon over a local meridian. The period of the mean lunar day, approximately 24.84 solar hours, is derived from the rotation of the earth on its axis relative to the movement of the moon about the earth.

1. (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. 2. In astronomy, the time required for the moon to revolve once, relative to a fixed star, about its own axis.

In space exploration, a lunar day is the period of time it takes for the Moon to complete one full rotation on its axis with respect to the Sun. Equivalently, it is the time it takes the Moon to make one complete orbit around the Earth and come back to the same phase. It is marked from a New Moon to the next New Moon.