Dry Mustard is Mustard Powder.
The dry mustard is mustard seeds that are ground down into mustard powder and used in recipes that call for the mustard powder.
The mustard powder is also used to make regular mustard that you buy in bottles or jars after being mixed with some other ingredients.
Dry mustard or mustard powder can be bought at just about any grocery store and is found in the spice aisles.
You can use the mustard powder to flavor stews, soups or even add to chili or even make your own mustard.
I like using mustard powder or dry mustard in soups, stews and chili to add mustard flavor to those dishes and it makes the food taste much better.