Pluto

A small horse is a horse.

A fat cat is a cat.

A dwaft planet, guess what, IS A PLANET

The argument says a sea horse is not a horse.

But sea horses and horses are not similar biological entities, nor have similar composition or evolutionary history.

However, the classification of celestial bodies as "planets" vs "dwarf planets" isn't based on their material composition

One could reasonably argue that a dwarf planet is a type of planet that fails to meet one specific criterion, rather than being a completely separate category.

It's either a misuse of grammar, or pluto is a class/type of planet.

If earth was moved to the kuiper belt would it still be a planet?