Wordnet 3.0
NOUN (2)
1.
an opaque watercolor prepared with gum;
2.
a watercolor executed with opaque watercolors mixed with gum;
The Collaborative International Dictionary of English v.0.48:
Gouache \Gouache\ (gw[.a]sh), n. [F., It. guazzo.]
A method of painting with opaque colors, which have been
ground in water and mingled with a preparation of gum; also,
a picture thus painted.
[1913 Webster]
WordNet (r) 3.0 (2006):
gouache
n 1: an opaque watercolor prepared with gum
2: a watercolor executed with opaque watercolors mixed with gum