Meaning

noun a ridge of sand created by the wind; found in deserts or near lakes and oceans

originPartly from a dialectal form of down; and partly from Dutch duin (from Middle Dutch dune) or from Middle Low German dûne; all ultimately from Proto-West Germanic *dūn, *dūnā, of uncertain origin; possibly from Proto-Celtic *dūnom (“stronghold, rampart”), from Proto-Indo-European *dʰuHnom (“enclosure”), from *dʰewh₂- (“to finish, come full circle”). Doublet of down (which see).

Etymology from Wiktionary, CC BY-SA 3.0