AI Glossary · Definition
What is Hallucination?
Hallucination: A hallucination is an AI output that sounds plausible but is false or unsupported, such as an invented fact, quote, figure or source.
By DAIDU EditorialUpdated
Hallucination, explained
Hallucinations happen because language models generate likely-sounding text rather than looking up verified facts. They are more common when a question asks for specific details the model does not have, such as recent events, niche figures or citations. You reduce the risk by grounding answers in your own documents, asking the model to say when it does not know, requiring sources, and having people check facts before anything is published or sent. No current model is free of hallucinations.
Example
An assistant invents a regulation number when asked about licensing rules; a reviewer catches it by checking the official source.