- (in deserts, esp the Sahara) a long ridge of blown sand, often several miles long
seif, from Arabic: sword, from the shape of the dune
- 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.