What is one word to describe william?

It's impossible to give a single word to describe William without more context! "William" is a common name, and to describe someone named William, you'd need to know more about them.

For example:

* William Shakespeare: "Playwright"

* William the Conqueror: "King"

* William Shatner: "Actor"

Tell me more about the William you're thinking of, and I can give you a more specific word.