What is velouté

Per the above comments veloute is (as is bechamel) a mother sauce; in other words you keep building on it. If it breaks "mount" it with more butter. Why do sauces in restaurants taste better than the ones you looked up on the internet? In a real restaurant they use tons of butter and buckets of salt.

You might find this posting of interest: http://food52.com/hotline/3027-whats-the-difference-between-a-jus-lie-and-a-veloute

to be a stickler about it, its stock that is thickened with roux not the other way around. and really it doesn't need to be stock it can be any sort of base thickened with roux

As opposed to a béchamel, which is prepared with milk rather than stock, be it vegetable, chicken, or beef.

It's a roux (butter, flour that are cooked) thickened with stock.