cul-de-sac

Short definition from Wiktionary

Noun

1. 1
   A blind alley or dead end street.
2. 2
   A circular area at the end of a dead end street to allow cars to turn around, designed so children can play on the street, with little or no through-traffic.
3. 3
   An impasse.
4. 4
   A sacklike cavity, a tube open at one end only.
5. 5
   Alternative form of cul-de-sac.