What exactly is called a major depressive disorder ?

Depression: It is clinical depression or mood disorder with vegetative signs and symptoms, such as appetite/sleep/energy changes, mood changes such as anxious/sad, and cognitive changes such as concentration/memory.

MDE: The dsm-iv criteria for major depression can be found at the following website: http://www.Mental-health-today.Com/dep/dsm.Htm it should be noted that major depression is a medical illness that is not the same as simply feeling sad or moody. Sadness is a normal response to certain situations, such as loss of a loved one, and is not necessarily major depression.