Rotating at exactly the same rate as the orbital period around some other body. E.g., the Moon rotates synchronously, relative to the Earth, so that its orbital period and rotational period are exactly the same. As a result, it always keeps one side (the near side) towards the Earth, and the Earth is always in very nearly the same place in the lunar sky (the position depending upon where you are, on the Moon). However, it does still rotate relative to the Sun and stars, at a rate equal to its rotation period, relative to the stars, and equal to its synodic period of rotation, relative to the Sun.
A satellite's rotational period is equal to its orbital period; this causes the same side of a satellite to always face the planet. Synchronous rotation occurs when a planet's gravity produces a tidal bulge in its satellite. The gravitational attraction and bulge acts like a torque, which slows down the satellite until it reaches a synchronous rotation.