[rors]

Perplexity is term from information theory. It's one measure of the quality of an LM. I.e. how perplexed is my model? To an experienced researcher it's a unit of measurement like metres or kg. https://en.wikipedia.org/wiki/Perplexity

I agree that it doesn't transfer out of that specialised domain.

[Aloisius]

Eh. Still a weird name given one generally wants to reduce perplexity.

Might as well call it Uncertainty.