What is the definition or description of: major depression?

Persistent sadness: Major depression is a mood disorder where a person is persistently sad or depressed for at least two weeks with changes in sleep, appetite and weight. Change in mood could also present as irritability. Low energy or persistent lethargy is also seen. Hopelessness and disinterest in enjoyable activities is common. Suicidal ideation is a sign of worsening depression and warrants immediate attention.

Major Depression: is a mood disorder lasting a minimum of two weeks. Depressive sx's may include low mood, irritability, anger, ^ or v sleep, change in appetite, feelings of helplessness or hopelessness, v energy, v self-esteem, feelings of guilt. V motivation, absence of joy,v concentration, v memory & suicidal thoughts.