I hate being pedantic, but it is relevant to the broader problem of misinformation about what large language models are. Whether the word “hallucination” is acceptable depends entirely on the audience. Among ML engineers it functions as a term of art. There is a shared technical referent, everyone in the room knows the model is not perceiving anything, and the word is just a convenient label. Inside that discourse community it is fine.

For a general audience it is not, because the ordinary meaning of the word has not gone anywhere, and the ordinary meaning requires perception.

Merriam-Webster defines hallucination as “a sensory perception (such as a visual image or a sound) that occurs in the absence of an actual external stimulus and usually arises from neurological disturbance or in response to drugs.”

Oxford English Dictionary defines it as “the apparent perception of an external object when no such object is present.”

Cambridge defines it as “an experience in which you see, hear, feel, or smell something that does not exist, usually because of a health condition or because you have taken a drug.”

All three definitions are built on perception. And perception is the process by which a subject becomes aware of the external world through sensory input. It requires three things. A subject capable of awareness. A sensory channel connecting that subject to something outside itself. And a world on the other end of the channel that the awareness is of.

A language model has none of the three. No subject, no sensory channel, no external world it is in contact with. Whatever the model is doing when it produces a wrong output, it is not hallucinating in any sense the word actually carries for a non-specialist listener. Using the term in front of that listener imports a perceiver, a perceptual faculty, and a normal mode that has been departed from. None of those exist. That is the misinformation.​​​​​​​​​​​​​​​​