“[C]ertainly when the 12th volume of A Series of Unfortunate Events came out, which was called The Penultimate Peril, I found that there were people who knew what that word [‘penultimate’] meant and people who didn’t, but that that line was not along age lines at all. I remember there was an article in a newspaper that said, ‘It’s the penultimate book from the penultimate author.’ They were just sort of using the word as some kind of placeholder, whereas children learned quickly what it meant and were more quick to adopt it.
“You see failed vocabulary in the adult world so often, and it’s often because once you reach a certain age you’re kind of embarrassed to go look up a word if you don’t know what it means. And then you just start using it however it feels right. . . . I think children are less embarrassed to go look up the truth.”
From an interview at NPR