1 [cartography] In cartography, portraying cartographic updates on a map by printing new or modified information over the original cartography, usually in a distinctive color.
2 [printing] In offset printing, printing a color on top of areas already inked with a different color. Overprinting is often used to print thin lines, such as contours, or small intricate graphics, such as text characters, to reduce the effect of registration problems. Overprinting can also be used to create the effect of mixing two colors where they are coincident. For example, yellow printed over cyan will appear green.