impasse

Impasse comes from French in- (not) and passer (to pass). It is literally 'a place where you cannot pass.' Parisian streets laid out in the 1700s included deliberate dead ends—short passages that led nowhere, used for storage or workshops or servants' quarters. These weren't mistakes. They were designed as such.

The French named them impasses. The word appeared in Parisian maps and street signs. An impasse was not a failure of urban planning; it was a feature, a useful dead end where traffic couldn't rush through. The architecture acknowledged the reality: some paths lead nowhere, and that's fine.

English borrowers faced a problem. We needed the word—we had dead-end streets and cul-de-sacs—but we didn't have the French ease with naming the trap. We called them dead ends, cul-de-sacs (from French but literally 'bag bottom'), or bottlenecks. Impasse came over as a metaphor only: a situation in which progress stopped.

Now impasse means a deadlock in negotiation, a conflict with no clear resolution. The physical fact (a street that ends) has become a political one (an agreement that can't move forward). The French still use impasse for actual streets. English uses it for metaphorical ones—situations where forward motion is impossible.