1 a: the angular distance of a celestial object below the horizon b: the size of an angle of depression 2: an act of depressing or a state of being depressed: as a: a pressing down :loweringb (1): a state of feeling sad :dejection(2): a psychoneurotic or psychotic disorder marked especially by sadness, inactivity, difficulty in thinking and concentration, a significant increase or decrease in appetite and time spent sleeping, feelings of dejection and hopelessness, and sometimes suicidal tendencies c (1): a reduction in activity, amount, quality, or force (2): a lowering of vitality or functional activity 3: a depressed place or part :hollow 4:low 1b 5: a period of low general economic activity marked especially by rising levels of unemployment