The Collaborative International Dictionary of English v.0.48:

Cul-de-sac \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.]
   [1913 Webster]
   1. A passage with only one outlet, as a street closed at one
      end; a blind alley; hence, a trap.
      [1913 Webster]

   2. (Mil.) a position in which an army finds itself with no
      way of exit but to the front.
      [1913 Webster]

   3. (Anat.) Any bag-shaped or tubular cavity, vessel, or
      organ, open only at one end.
      [1913 Webster]