Hallucination

The model confidently stating things that aren't true — inventing a citation, a person, a number. Not lying (it has no intent); it's producing plausible-sounding text, and plausible isn't the same as true.

The scene that explains it: the business cards in American Psycho. Immaculate stock, perfect lettering, delivered with total confidence — and completely hollow. A hallucination is that card. The finish is flawless, which is exactly why nobody checks.

Why it matters: the single biggest risk in putting AI in front of customers. A confident wrong answer is far more dangerous than an honest "I don't know" — you cannot take an AI feature to real users until you know how often, and how loudly, it's wrong.