n (psychology) in psychotherapy and psychiatry, a state of mind producing serious, long-term lowering of enjoyment of life or inability to visualize a happy future
n (psychology) in psychotherapy and psychiatry, a period of unhappiness or low morale which lasts longer than several weeks and may include ideation of self-inflicted injury or suicide
n (meteorology) an area of lowered air pressure that generally brings moist weather, sometimes promoting hurricanes and tornadoes
n (biology|physiology) a lowering, in particular a reduction in a particular biological variable or the function of an organ, in contrast to elevation