1. a class of mental and behavioral disorders in which the development of symptoms is related to the presence of some environmental stressor or life event and is expected to remit when the stress ceases;
2. a disorder whose essential feature is a maladaptive reaction to an identifiable psychological stress, or stressors, that occurs within weeks of the onset of the stressors and persists for up to six months; the maladaptive nature of the reaction is indicated by impairment in occupational (including school) functioning, or in usual social activities or relationships with others, or with symptoms that are in excess of a normal or expectable reaction to the stressor.