Hallucination
A confident but factually wrong or fabricated output from an LLM. Grounding via RAG, output validation, and citation-required prompting reduces but does not eliminate hallucination. Rate is a key production quality metric.
Related terms
- Groundedness
A measure of how well an LLM output is supported by provided source material. High-groundedness answers cite or paraphrase provided context; low-groundedness answers introduce claims not present in sources. A primary target metric for RAG systems.
- Retrieval-Augmented Generation (RAG)
A pattern where an LLM answers a query by first retrieving relevant documents from an external corpus (typically via a vector database or hybrid search) and injecting them into the prompt as grounding context. RAG addresses freshness and factual grounding without model retraining.
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Where this fits
Hallucination is part of the Evaluation & Governance vocabulary used in the Generative AI Maturity Framework. See the full glossary for the complete set of 149 defined terms, or take the free maturity assessment to see where your organisation stands.