Why is gumbo called gumbo?

Gumbo is a soup or stew made in Louisiana that can be made with a Roux which is flour and grease browned together and then when you get it as dark as you want it, then you add water or broth. You always have the trinity which is onion, bell pepper, and celery sauteed in it, and you add tomatoes. Okra is optional. Then, depending on what kind of gumbo you are making you add seafood, duck, chicken, alligator, sausage, or any combination of things, and cook it several hours and traditionally it is served over rice or you can have it as a delicious soup.