What is the term for a smaller body that orbits a planet?

The term for a smaller body that orbits a planet is "Moon." In astronomical terms, a moon is defined as a natural satellite that orbits a larger body, typically a planet. Moons vary in size, composition, and characteristics but are primarily categorized as natural celestial bodies that form through processes such as accretion or capture.

This distinction sets moons apart from other objects, such as asteroids, which generally orbit the Sun and are not specifically tied to the gravitational influence of a planet, or comets, which are icy bodies that develop a tail when close to the Sun. While the term "satellite" can also refer to any object in orbit around another body—including artificial satellites—this is a broader classification that also encompasses moons. However, in the context of natural bodies specifically orbiting planets, "moon" is the most precise term.