(in deserts, esp the Sahara) a long ridge of blown sand, often several miles long
Word Origin for seif dune
seif, from Arabic: sword, from the shape of the dune
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
A sharp-crested longitudinal sand dune or chain of sand dunes common to the Sahara and ranging up to 300 m (984 ft) in height and 300 km (186 mi) in length.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.