Gouache is a kind of paint that some artists use. When you paint with gouache, you mix it with water. However, unlike watercolors, it’s not translucent.
Commercial artists often choose to use gouache for illustrations or posters. It has many qualities of watercolor paints (you can add water to thin it, and it dries matte rather than glossy), but the final effect is completely opaque, like acrylics or oil paints. You can also call the painting that results from using these paints a gouache. The word simply means “watercolor” in French, from the Latin root aquatio, “watering place.”
an opaque watercolor prepared with gum
a watercolor executed with opaque watercolors mixed with gum