What is a dwarf planet?

The word dwarf means something that has not grown fully. The dictionary defines it as “of less than expected stature.”

Accordingly, a dwarf planet is a planet that is not large enough to be a planet.

According to the International Astronomical Union, which sets definitions for planetary science, a dwarf planet is:

A celestial body that:

A. orbits the sun,

B. has enough mass to assume a nearly round shape,

C. has not cleared the neighborhood around its orbit, and

D. is not a moon.

Is Pluto the only dwarf planet in our solar system?

As NASA informs us, NO.