Something abstruse is hard to understand, and often it feels as if it did not need to be that hard. A lecture, a theory, a paragraph stuffed with rare words — if you finish it and still feel shut out, that is abstruse. It is a learned, slightly cool adjective, at home in reviews and academic grumbling, and it often carries a hint of complaint: this did not need to be so closed. A philosophy page can be abstruse; a locked door is not. A maths proof may be abstruse; a heavy box is merely hard to lift. People stretch it toward “anything I found difficult,” and that is looser than the centre. Keep it for ideas and writing. Though actually, the Latin picture is “pushed away, hidden,” so the old idea is “not out in the open,” not “clever.” It is also not the same word-family as abstract, however similar they look. Both begin with Latin abs- “away,” but abstract is “pull away” and abstruse is “push away / hide.” An abstract idea has been lifted out of particular things; an abstruse idea has been shoved out of easy reach.

艱深、晦澀