Diderot coined the term, literally translating to “staircase idea” (Wikipedia suggests “afterwit”). You are having a discussion, your opponent makes a stinging remark, you are unable to suitably respond. You leave the dinner party and as you are coming down the stairs, it comes.
“Esprit d’escalier” is a particular species within the genus of untimely remarks. Other notable instances:
– I wish I’d had the courage to say it when I though of it
– I liked saying it so much I wish the moment would come again
– I wish life would present me with the occasion to say this at least once
In general, this is a space of regret, passive-aggressive ideation, desire to escape oneself and petty vanity. It is also a space where I spend a lot of time.