The word is in most online dictionaries for what it is worth. It's also used in Biblical texts, albeit only a handful of times. I do agree it's not a true assessment of an LLM's overall reasoning. No person I have ever asked that riddle to has gotten it correct. Then again, that is probably partly the point of the riddle.

I would like to reiterate that both Claude and GPT answered correctly. It was just bizarre how Claude got a initial, minor detail incorrect, but reasoned enough to get the more difficult answer correct.