As a non-native English speaker there are 4 words in this article that I had to look up, which is significantly higher than a typical article from HN frontpage (usually it's 0, occasionally 1).
If anyone curious, the words are: pellucid, fusillades, pram (idk, why I never heard it. I knew the word "stroller", of course, but I never thought about different kinds of strollers), octogenarian (this one I could have guessed from Latin roots and context, was lazy).