Cul-de-sac

Webster's Dictionary of the English Language

·noun Any bag-shaped or tubular cavity, vessel, or organ, open only at one end.

II. Cul-de-sac ·noun a position in which an army finds itself with no way of exit but to the front.

III. Cul-de-sac ·noun A passage with only one outlet, as a street closed at one end; a blind alley; hence, a trap.