choropleth map

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A thematic map in which the distribution of some property is shown using different colours

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a map that uses graded differences in shading or color or the placing of symbols inside defined areas on the map in order to indicate the average values of some property or quantity in those areas