A color ground with water and gum or other glutinous medium; a color the vehicle of which is water; -- so called in distinction from
oil color. [
1913 Webster]
" It preserves its consistency when dried in a solid cake, which is used by rubbing off a portion on a moistened palette. Moist water colors are water colors kept in a semifluid or pasty state in little metal tubes or pans."
[1913 Webster]