{
  "id": "hallucination",
  "code": "PTL-0096",
  "term": "Hallucination",
  "aliases": [
    "confabulation",
    "fabrication"
  ],
  "category": "failure-modes",
  "definition": "Hallucination is generated content that is fluent and plausible but unfaithful to the provided source or factually incorrect, such as fabricated citations, facts, or quotations.",
  "description": "Surveys distinguish intrinsic hallucination, which contradicts the source, from extrinsic hallucination, which cannot be verified from it. Mitigations include retrieval-augmented generation, verification methods such as chain-of-verification, allowing the model to say it does not know, and requiring quotes from supplied documents.",
  "example": null,
  "broader": [],
  "narrower": [],
  "related": [
    "retrieval-augmented-generation",
    "chain-of-verification",
    "sycophancy"
  ],
  "introduced": null,
  "sources": [
    {
      "title": "Survey of Hallucination in Natural Language Generation",
      "authors": "Ji et al.",
      "year": 2022,
      "url": "https://arxiv.org/abs/2202.03629"
    }
  ],
  "url": "https://protologue.com/t/hallucination/",
  "citation": "Protologue. (2026). Hallucination. In Protologue: A Taxonomy of Prompting and LLM Techniques (v1.0.0, PTL-0096). https://protologue.com/t/hallucination/"
}