Real Dictionary

pointillism in American English
the method of painting of certain French impressionists, in which a white ground is systematically covered with tiny points of pure color that blend together when seen from a distance, producing a luminous effect
noun: a theory and technique developed by the neo-impressionists, based on the principle that juxtaposed dots of pure color, as blue and yellow, are optically mixed into the resulting hue, as green, by the viewer

pointillism in British English
noun: the technique of painting elaborated from impressionism, in which dots of unmixed colour are juxtaposed on a white ground so that from a distance they fuse in the viewer's eye into appropriate intermediate tones