I find that explaining errors and factual mistakes in LLMs or AI in general as hallucinations to be counter-productive. I don't know if the field has landed on a specific definition of what hallucination is, but I mostly associate it with garbled output from tokens like 'SolidGoldMagicKarp'[0] and 'davidjl'[1].
My understanding is that AI models like GPT have been able to convincingly convey the form of language, but not its meaning. It looks and sounds like how a human would communicate, but the AI is unable to imbue meaning into the words and sentences it produces. My knowledge of this comes from Lex Friedman's episode with Edward Gibson [2].
I think that's the fundamental issue with LLMs at the moment. It has managed to mostly exit the uncanny valley because, as far as most people are concerned, the text produced could just as well have been made by a human. I think this lends some credibility to the text produced by the LLM, because more or less all text ever produced has had a human behind it. This is no longer the case and as such there is bound to be a transitional period where we learn how to deal with this new technology.
[0]: https://www.lesswrong.com/posts/aPeJE8bSo6rAFoLqg/solidgoldm...
[1]: https://twitter.com/goodside/status/1666598580319035392
[2]: https://youtube.com/watch?v=F3Jd9GI6XqE&t=230