What is the term used for the situation when a body rotation and it's revolution take the same time

The moon is a little different. The moon rotates once about every 27 days, and revolves once about every 27 days. So every time the moon goes around Earth it turns around one time. That is why the moon always looks the same - we only ever see one side of it! Another strange thing is that if we lived on the Moon and thought of days and years the same way we do on Earth, a day AND a year would be the same length! Since the rotation and revolution times are the same, the length of a day and the length of a year are identical.