hallucination

Etymology

Derives from the verb hallucinate, from Latin hallucinatus. Compare French hallucination. The first known usage in the English language is from Sir Thomas Browne.

noun

1. A sensory perception of something that does not exist, often arising from disorder of the nervous system, as in delirium tremens.
   Hallucinations are always evidence of cerebral derangement and are common phenomena of insanity. 1871, William Alexander Hammond, A Treatise on the Diseases of the Nervous System
   The authorities said that the spinach had caused “possible food-related toxic reactions” with those affected experiencing symptoms including delirium, hallucinations, blurred vision, rapid heartbeat and fever. 2022-12-18, Yan Zhuang, “How Can Tainted Spinach Cause Hallucinations?”, in The New York Times, →ISSN
2. The act of hallucinating; a wandering of the mind; an error, mistake or blunder.
3. (artificial intelligence) A confident but incorrect response given by an artificial intelligence.
   Chatbots even forget that they are a bot and experience "hallucinations", Meta's description for when a bot confidently says something that is not true. 2022-08-08, Liam Tung, “Meta warns its new chatbot may forget that it's a bot”, in ZDNET
   Hallucinations are about adhering to the truth; when A.I. systems get confused, they have a bad habit of making things up rather than admitting their difficulties. 2022-12-16, Farhad Manjoo, “ChatGPT Has a Devastating Sense of Humor”, in The New York Times, →ISSN
   It may tell you that the official currency of Switzerland is the euro (it’s actually the Swiss franc) or that Mark Twain’s Celebrated Jumping Frog of Calaveras County could not only jump but talk. A.I. researchers call this generation of untruths “hallucination.” 2023-01-10, Cade Metz, “A.I. Is Becoming More Conversational. But Will It Get More Honest?”, in The New York Times, →ISSN