||Cul`-de-sac" (ku`de-s?k" or kul`de-s?k"), n.; pl. Culs-de-sac (ku`- or kulz`-). [ F., lit., bottom of a bag.]

1. A passage with only one outlet, as a street closed at one end; a blind alley; hence, a trap.

2. (Mil.) a position in which an army finds itself with no way of exit but to the front.

3. (Anat.) Any bag-shaped or tubular cavity, vessel, or organ, open only at one end.

• A blind alley or dead end street.
  
• (US): A circular area at the end of a dead end street to allow cars to turn around, designed so children can play on street, with little or no through-traffic.
  
• An impasse.
       quotations:
       *"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." — National Review, February 14, 2005
  
• (medicine) A sacklike cavity or tube open at one end only.