What is the name for a rock orbiting the Sun between the orbits of Mars and Jupiter?
The orbits between Mars and Jupiter is where you find a large proportion of asteroids.
By no means are all asteroids orbiting between Mars and Jupiter. The term "asteroid" has come to mean any small, rocky object in orbit around the Sun. The orbits between Mars and Jupiter contain lots of asteroids because there's not a planet there to clear that zone. But we also have asteroids orbiting in tandem with Jupiter (Trojan asteroids) and a few among the inner planets. Some asteroids pass near Earth and are tracked closely for possible collisions (https://en.wikipedia.org/wiki/Near-Earth_object).
Among the asteroids otbiting beteeen Mars and Jupiter one is especially large, massive and fully rounded by its own gravity. Thus Ceres has been "promoted" to a dwarf planet.