What exactly does it mean to be clinically depressed?

Depression symptoms: Symptoms of depression include: a loss of interest in activities you used to enjoy, difficulty concentrating, change in sleep and/or appetite, fatigue, feelings of hopelessness, sadness, poor motivation, irritabiliy and an impaired ability to function. If you think you may be depressed, see you doctor. Medical causes should also be ruled out to obtain an accurate diagnosis.

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.