Maybe the rest of you already knew this one?
Ultracrepidarianism: the act of believing that your (real) expertise in one area makes you an expert in other (unrelated) fields.
Ultracrepidarian: a person committing this blunder.
How is it possible that I didn’t know that word until now? Talk about a useful word and concept!
We should have a shorter, easier-to-pronounce word for this, the better to point at someone and say, “You’re stumbling into ultracrepidarianism right now, Bob. Cut it out.”