cul-de-sac

noun4

1. •
   A blind alley or dead end street.

   • His was the end house of a cul-de-sac, with the side wall of a huge brewery beyond. — 1925
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.

   • And in suburbs known for new development, preservationists are often battling a general perception that there is nothing historic or worth saving among the cul-de-sacs. — 2010
3. •
   A sacklike cavity, a tube open at one end only.
4. •
   (figurative) An impasse.

   • Physics seems, in fact, to have got itself into a cul-de-sac, obsessing over theories so mathematically abstruse that nobody even knows how to test them. — 2005