What does the root word pachy mean?

The root word "pachy" comes from the Greek word "παχύς" (pakhys), meaning thick or stout.

It's often used in biological terms to describe something thick or bulky, like:

* Pachyderm: A mammal with thick skin, like an elephant or rhinoceros.

* Pachymeninges: The outer layer of membranes surrounding the brain and spinal cord.

However, it can also be used more generally to describe something thick or dense:

* Pachymeter: An instrument for measuring the thickness of objects.

* Pachymetry: The measurement of the thickness of something, often used in eye exams.

So, essentially, "pachy" means thick in most contexts.