BLUE, adjective blu. One of the seven colors, into which the rays of light divide themselves, when refracted through a glass prism. There are various shades of blue as sky-blue, or azure, Prussian blue indigo blue smalt blue etc.
Prussian blue a combination of the oxyd of iron with an acid called ferro-prussic.
BLU'E, verb transitive To make blue; to dye of a blue color; to make blue by heating, as metals etc.