the shape made by the amount of the moon that you can see at a particular time:
There's no moon (= you cannot see the moon) tonight.
a crescent/full/new moon
a similar round object that moves around another planet:
Jupiter has at least 16 moons.
to show your naked bottom in public, as a joke or as a protest :
Two male juveniles were arrested and charged with indecent exposure after they mooned a police officer.
the object, similar to a planet, that moves through the sky, circling the earth once every 28 days, and which can often be seen clearly at night when it shines with the light coming from the sun:
[ U ] the full moon
A moon is also a similar object that moves around another planet:
[ C ] Jupiter has at least sixteen moons.
to move or spend time in a way that shows a lack of care and interest and no clear purpose:
She’s been mooning around the house all weekend.