Meaning of “moon” - Learner’s Dictionary

moon

noun uk us /muːn/
the moon

A2 the round object that shines in the sky at night and moves around the Earth

crescent/full/new moon

the shape made by the amount of the moon that you can see at a particular time

[ C ] a round object like the moon that moves around another planet:

The planet Saturn has eighteen moons.

(Definition of “moon” from the Cambridge Learner’s Dictionary © Cambridge University Press)