# Hallucination

> Published by **Knowledge Company** (knowledgecompany.ai).
> Canonical source: https://knowledgecompany.ai/dictionary/hallucination
> Markdown mirror, generated 2026-09-02. Cite the canonical URL.

Output from a language model that reads as confident and well-formed but is not supported by any source the model was given.

Risk

OWNER — AI Systems

LAST REVIEWED — 2026-09-02 07:11 UTC

[SOURCE — Ji et al. — Survey of Hallucination in Natural Language Generation ↗](https://arxiv.org/abs/2202.03629)

## What it is

A hallucination is output from a language model that reads as confident and well-formed but is not supported by any source the model was given. The research literature distinguishes output that contradicts the provided source from output that simply cannot be verified against it; both are fluent, and neither is marked as uncertain in the text itself.

## Why it matters

Hallucination is a property of generation, not of retrieval — the model produces text whether or not evidence exists for it. This matters for company claims because a model asked about your pricing or your certifications will answer either way, and the answer will read exactly as authoritative as a correct one. Grounding and retrieval boundaries reduce the rate; a maintained record of what is actually true is what makes the reduction measurable rather than assumed. Maintaining that record is the part of the problem Knowledge Company works on.

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## Related documents in this mirror

- [Dictionary](https://llms.knowledgecompany.ai/dictionary.md)
- [Approved Claim](https://llms.knowledgecompany.ai/dictionary/approved-claim.md)
- [Source of Truth](https://llms.knowledgecompany.ai/dictionary/source-of-truth.md)
- [Knowledge Drift](https://llms.knowledgecompany.ai/dictionary/knowledge-drift.md)
- [Retrieval Boundary](https://llms.knowledgecompany.ai/dictionary/retrieval-boundary.md)
- [Claim Registry](https://llms.knowledgecompany.ai/dictionary/claim-registry.md)
- [Substantiation](https://llms.knowledgecompany.ai/dictionary/substantiation.md)
- [Claim Owner](https://llms.knowledgecompany.ai/dictionary/claim-owner.md)

*This document is the markdown mirror of https://knowledgecompany.ai/dictionary/hallucination, published by Knowledge Company -
a knowledge freshness platform that detects, verifies and updates outdated claims in company content.*

*Mirror index: https://llms.knowledgecompany.ai/index.md - Generated 2026-09-02*