Depression may be described as feeling sad, blue, unhappy, miserable, or down in the dumps. Most of us feel this way at one time or another for short periods.<unk>  is a mood disorder in which feelings of sadness, loss, anger, or frustration interfere with everyday life for a longer period of time.
Clinical depression
Depression 
Post travel depression
Atypical depression
Post stroke depression
Suicide ideation
Melancholic depression
Psychotic depression