In chapter 9, Emma and Harriet are engaged in collecting riddles, puzzles, and conundrums. The vapid and goofy Mr. Elton suggests this:
Emma regretfully tells him that they’ve already got that one, but Austen doesn’t give us the answer. Having no head for this sort of thing myself, I can’t figure it out, beyond the fact that the solution is apparently a compound word. I’ve read Emma at least a dozen times, and not knowing the answer has never bothered me, but for some reason on this re-read it’s driving me nuts. Any guesses?