Used in a general way to speak of any of the depressive illnesses It is a taxonomic term that does not capture the sadness and dread that are at the core of depression
A mental disorder characterized by a consistent, pervasive alteration in mood, and affecting thoughts, emotions, and behaviors. Mental disorder characterized by dramatic changes or extremes of mood. Affective disorders may include manic or depressive episodes less severe than those of bipolar disorder. Symptoms include elevated, expansive, or irritable mood, with hyperactivity, pressured speech, and inflated self-esteem; and/or dejected mood, with lack of interest in life, sleep disturbances, agitation, and feelings of worthlessness or guilt