\Dune\, n. [The same word as down: cf. D. duin. See {Down}
a bank of sand.]
A low hill of drifting sand usually formed on the coats, but
often carried far inland by the prevailing winds. [Written
also {dun}.]

      Three great rivers, the Rhine, the Meuse, and the
      Scheldt, had deposited their slime for ages among the
      dunes or sand banks heaved up by the ocean around their
      mouths.                                  --Motley.