What are the root words of pneumonoultramicroscopicsilicovolcano...?

The word you are referring to is pneumonoultramicroscopicsilicovolcanoconiosis, a made-up word that was created as a humorous example of a very long word. While it's not a real medical term, it is constructed from real words:

* Pneumono-: From the Greek word "pneumon", meaning "lung".

* Ultra-: Latin for "beyond", indicating something very small.

* Microscopic-: Referring to something visible only under a microscope.

* Silico-: From the Latin word "silex", meaning "flint", referring to silica.

* Volcano-: From the Latin word "volcano", referring to a volcano.

* -Coniosis: A suffix meaning "dust", specifically the condition of dust in the lungs.

So, the word is a combination of Greek and Latin roots, essentially describing a lung disease caused by inhaling very fine silica dust, possibly from a volcanic eruption.