hallucination

Definition

Producing content that is fluent, confident, and false. It is structural rather than incidental: next-token training rewards plausible continuations, and nothing in that objective requires a continuation to be true. Mitigations therefore come from outside the objective — grounding answers in retrieved documents, or verifying claims after generation. The failure is about truth, not about grammar or fluency.

Explainers using this term

• Why Language Models Hallucinate — The Mechanics and What Actually HelpsSurvey of Hallucination in Natural Language Generation