As others have pointed out, too many clicks per word. I am a sucker for a 'how many words do you know' quiz so I finished anyway. Overall I'm skeptical of the classifications. In broad strokes, the early words are easier and the latter words are more challenging, but the middle is pretty muddied. Some of the words chosen are rather absurd/inappropriate: breviary (which I got wrong but felt like a vaguely religious wo…
I'll contest a few of these, which I thought were good. Breviary: this was, to me, known and not uncommon. It's widely known to Catholics, but also, if you have an interest in medieval art or books, you'd likely know it too. It was one of the main types of books before the invention of the printing press. Think of an image from an illuminated manuscript, 50% chance it's from one. Hippopotomonstrosesquippedaliophobia:…
I'll remark that "if you have interest in [some particular academic pursuit], you'd likely know it" is a pretty decent description of the sort of word that shows up in "grandmaster" tier.
(I have joked that, living in Japan, my English is getting worse faster than my Japanese is getting better, but breviary might well be a concrete example.)