A precise, concise definition of good writing

In my writing classes, I tell students that good writing is first precise, but also concise. That means choosing exactly the right word/phrase, while also using as few words and sentences as possible. It means there's nothing left out that's necessary to convey exactly the right meaning, but nothing added in that's superfluous, either.

Sure, there's more to it than that. But "precise and concise" is a good place to start.