Definitions for "Major depressive disorder"
Syndrome characterized by one or more major depressive episodes without a history of manic, mixed, or hypomanic episodes.
Mental disorder lasting at least 2 weeks, in which a person shows extreme sadness, loss of pleasure or interest in life, and such other symptoms as weight changes, insomnia, feelings of worthlessness or inappropriate guilt, loss of memory, inability to concentrate, and thoughts of death or suicide. (561)
A mood disorder involving periods of sadness, lasting at least 2 weeks, which can include symptoms such as feeling down most of the time, appetite and sleep changes, loss of pleasure in activities that were once enjoyable, and not wanting to live.