語彙力 goiryoku

語彙力 is a normal, respectable word: vocabulary power, the kind of thing a school report might comment on. Online it appears almost exclusively in the negative, because the internet found a better use for it. 語彙力がない, my vocabulary is gone, is what you write when something is so good that adjectives have deserted you.

There is a neater version still. Post an incoherent reaction, then add 語彙力 alone in brackets, and the bracket does the work of an apology, a joke and a footnote at once. It is a very Japanese move: acknowledging that you have failed to express yourself, in a way that expresses it perfectly.