To engage in an activity other than what one is known for.
To work on the side (at a secondary job), often in the evening or during the night.
To perform a secondary function substantially different from its supposed primary function, as in protein moonlighting.
The light reflected from the Moon.
To steal, especially by surreptitiously removing an unguarded item.
To make the strongest favorable impression in a theatrical or similar performance, in comparison to other performers.
To win, as in a contest and especially without significant effort.