depression Read more about depression (noun) - an area of land that is lower than its surroundings. Also, a time when the economy slows down.
democracy Read more about democracy (noun) - a form of government where the people rule, either directly or by voting for representatives
delta Read more about delta (noun) - a landform at the mouth of a river where it empties into a body of water
Declaration of Independence Read more about Declaration of Independence (noun) - the document recording the proclamation of the second Continental Congress (4 July 1776) asserting the independence of the Colonies from Great Britain
deciduous Read more about deciduous (noun) - a plant, especially a tree, that loses its leaves in the winter
dam Read more about dam (noun) - a large wall built across a river to change the natural flow of water and make a deep lake form behind the wall