Q. What is Nothing?

A: To understand what nothing is, you first have to know a little about sets and how the function of about half of all language deals with sets.

The primary structure of language is the 'thing', not the noun as commonly taught in public schools. You English teacher probably defined a noun this way:

A noun is a person, place, idea, or thing.

Actually, all of those are things and since the noun is an idea it is a thing.