Synchronous rotation is a 
planetological term describing a body 
orbiting another, where the orbiting body takes as long to rotate on it's 
axis as it does to make one orbit; and as such, always keeps the same hemisphere pointed at the body it is orbiting.
The Moon and the Earth have a synchronic relationship. In fact, most moons in the solar system have synchronous rotation due to tidal locking.
 
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