What is the term for a rocky object in space that varies in size and primarily orbits between Mars and Jupiter?

The correct term for a rocky object in space that varies in size and primarily orbits between Mars and Jupiter is indeed an asteroid. Asteroids are remnants from the early solar system, primarily found in the asteroid belt, which lies between the orbits of Mars and Jupiter. They can range in size from small boulders to objects that are hundreds of kilometers in diameter.

Meteoroids are smaller than asteroids and are typically fragments that can originate from asteroids or comets. Comets, on the other hand, are composed mainly of ice and dust and have distinct tails that form when they approach the sun. Planets are much larger celestial bodies that orbit the sun and have cleared their orbits, distinguishing them from smaller objects in the solar system. Thus, the correct identification of the object as an asteroid highlights its position and characteristics in relation to other types of celestial bodies.