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 coast, 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.
© Webster 1913.