l'esprit de l'escalier (French) is one of those great words that doesn't have a meaning in English. I love finding words like this, learning things that don't even have a word, but I know what it means and I can relate to it, and understand it. L'esprit de l'escalier is a way to describe that feeling you get when you think of the perfect thing to say, but it's too late. The perfect zinger, the most witty retort...just something appropriately fitting for the situation. But the moment is gone!
Here are some more words that don't exist in the English language, but you know exactly what they mean.