Originally Posted by sendec
An expert is a person who has mastered the basics and can perform them consistently under pressure, on demand and independent of luck, fate or Karma. They can explain how they do something and why. An expert can evaluate new data and reach a conclusion on its value on its own merits. An expert can continually teach, and continually learns.
I think that's the best definition in the thread.
Someone else commented that there's a difference between an instructor & an expert. That was my initial thought too, but after thinking about it longer it seems to me that there should not be such a difference -- especially if using Sendec's definition.