In French, the term cul-de-sac literally means "bottom of the bag." In English it usually refers to a dead-end street, but can also be applied to any pathway, for example a rock crevice, that only has one opening and is closed at the other end.
"Deep crevice in rock layers in the Worlds End State Park, Pennsylvania, USA, May 2009" by Ruhrfisch is licensed under CC BY-SA.
A06 People of Darkness (03-06) p. 262 A06 People of Darkness (03-06) p. 264
A07 The Dark Wind (04-06), p. 219
Merriam-Webster Online N.d. cul-de-sac. http://www.merriam-webster.com/dictionary/cul-de-sac, accessed June 18, 2015.
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