(1) a manifestation of a major mood disorder involving an enduring period of some or all of the following signs: significant sadness, tearfulness, decreased appetite, weight loss, sleep and energy disturbance, psychomotor agitation or retardation, feelings of worthlessness, guilt, helplessness, hopelessness, decreased concentration, thoughts of death, and suicidal ideation.major depression, bipolar disorder, affective disorders, under disorder. Cf.: manic episode (2) a DSM diagnosis that is established when specified criteria are met.