Gouache

gouache \ˈgwäsh\ noun: 1. a method of painting with opaque watercolors, 2. a picture painted by gouache, 3. the pigment used in gouache

Etymology: French, from Italian guazzo, literally, puddle, probably from Latin aquatio watering place, from aquari to fetch water, from aqua water

Of the few who know about gouache, fewer spell it correctly (including artists).