Type of satellite in-sync with another orbit

A quasi-satellite is an astronomical object that crosses a planet's orbit during its own orbit.

Diagram of a quasi-satellite's orbit

A quasi-satellite's orbit around the Sun takes exactly the same time as the planet's orbit. Its eccentricity is different from the eccentricity of the planet. The orbits of quasi-satellites are unstable and over time they will break free from the planet's gravity.