Gouache. I love the stuff, as well as the word. It is similar to water color but more opaque, silky in texture. It's wonderful for calligraphy with dip pens. It's just one item in the arsenal of mediums.
Then there is the "how to you pronounce that?" question. Here ya go!
Apparently I've been pronouncing it wrong myself. Dang!
I thought it was gwash, not gooash. I like my way better.
If you are interested in a more elaborate description here are a couple good ones I ran across.
Follow up on Black
This popped up the day after B day. Takes putting something black in the mix to a new & beautiful level.