Definition
AI hallucination
An AI hallucination is an output that sounds plausible but is false, unsupported, or disconnected from the provided sources. Hallucination is not only a model flaw; it can come from weak prompts, missing context, poor retrieval, or no human review.
Last updated: 25 June 2026
Why it matters
It turns quality control into an operating requirement, especially for legal, financial, medical, or customer-facing work.
Signals to watch
- Answers lack sources
- Facts cannot be verified
- The model invents names, numbers, or citations