Definitionen
1.NounA kitchen where everyday cooking is done by household staff, as distinct from a kitchen that is purely for show or for special use by the owner of the house.
2.NounA kitchen, sometimes auxiliary or situated outside the house, used primarily for preparing messy and smelly dishes or cooking with firewood or charcoal. It is also used for cooking for a large group of people.
3.Noun↑ “dirty kitchen, n.”, in OED Online , Oxford: Oxford University Press, June 2015.