nappe

[nap]
noun
  1. Geology. a large mass of rock thrust a considerable distance along a nearly horizontal fault plane or in an overturned anticlinal fold.
  2. Geometry. one of the two equal sections of a cone.

Origin of nappe

1905–10, Americanism; < French: literally, tablecloth, cloth; Old French nappe, nape < Latin mappa; cf. napkin
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British Dictionary definitions for nappe

nappe

noun
  1. a large sheet or mass of rock, commonly a recumbent fold, that has been thrust from its original position by earth movements
  2. the sheet of water that flows over a dam or weir
  3. geometry either of the two parts into which a cone (sense 2) is divided by the vertex

Word Origin for nappe

C20: from French: tablecloth
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012