It is used to describe a category of sausages that includes sausage such as “Blutwurst” (blood sausage), “Leberwurst” (liver sausage) and Zungenwurst (tongue sausage.)
The meat and / or offal used in the sausage is steamed or boiled, so that the sausage doesn’t need further cooking. It is ready to eat, and can be served cold or hot.
Many Kochwurst type sausages are intended to be used as a spread, or sliced for serving.
Despite not needing cooking, they may still need refrigeration.
The opposite of Kochwurst Sausages is Brühwurst Sausages.