A dead end, also known as a cul-de-sac (, from French for 'bag-bottom'), no through road or no exit road, is a street with only one inlet or outlet.

The term "dead end" is understood in all varieties of English, but the official terminology and traffic signs include many different alternatives. Some of these are used only regionally. In the United States and other countries, cul-de-sac is often not an exact synonym for dead end and refers to dead ends with a circular end, allowing for easy turning at the end of the road. In Australia and Canada, they are usually referred to as a court when they have a bulbous end.

Dead ends are added to road layouts in urban planning to limit through-traffic in residential areas. While some dead ends provide no possible passage except in and out of their road entry, others allow cyclists, pedestrians or other non-automotive traffic to pass through connecting easements or paths, an example of filtered permeability. The International Federation of Pedestrians proposed to call such streets "living end streets" and to provide signage at the entry of the streets that make this permeability for pedestrians and cyclists clear. Its application retains the dead end's primary function as a non-through road, but establishes complete pedestrian and bicycle network connectivity.