Hallucination
Also known as: hallucinations, confabulation
What is hallucination?
A hallucination is a confident, fluent model output that is factually wrong or fabricated. It is a structural property of next-token prediction, not a bug that a better prompt fully removes.
Mitigations that actually work
- Ground answers in retrieved source text and cite it
- Constrain output to a schema or an allowed set of values
- Add a verification step for high-stakes claims
- Give the model an explicit 'insufficient information' path
Last reviewed by the gAIcko editorial team.