Concept
Hallucination
Confident model output that is factually wrong, fabricated, or unsupported by sources.
Definition
Hallucinations occur because language models optimise plausibility, not truth. They blend memorised patterns to fill gaps, producing invented citations, fake APIs, or wrong dates. Retrieval-augmented generation, grounding, and instruction tuning reduce â but do not eliminate â this failure mode.
Common use cases
- Risk mitigation
- Trust calibration
- Safety review