Hallucination (AI)
Etymology
Borrowed from the medical and psychological term, from Latin "alucinari," to wander in the mind. Applied to AI in the 2020s, it describes a model generating content untethered from reality. The word is contested: critics argue it flatters the machine by implying a mind that perceives, when the system is only producing statistically likely text with no notion of truth at all.
noun · /huh-loo-suh-NAY-shun/
When an AI system states false information confidently, as if it were fact.
What it names
The defining failure mode of chatbots — plausible, well-worded answers that are simply made up.
Example
The chatbot’s hallucination invented a court case, complete with a convincing but fictional citation.
Related idea
A hallucination differs from an ordinary bug: it isn’t a broken rule but the system working exactly as designed — predicting plausible words — which is why fluency and confidence are no signal of correctness.
noun · /huh-loo-suh-NAY-shun/
A perception of something that is not actually present — a sight, sound, smell, or sensation with no external source.
What it names
the sensory experience, often from illness, exhaustion, or drugs.
Example
The high fever brought vivid hallucinations.
Related idea
The human meaning the AI usage borrows: confidently perceiving what isn’t there.