1. 1. The act of depressing.
   2. The condition of being depressed.
2. An area that is sunk below its surroundings; a hollow.
3. The condition of feeling sad or despondent.
4. Psychology. A psychiatric disorder characterized by an inability to concentrate, insomnia, loss of appetite, anhedonia, feelings of extreme sadness, guilt, helplessness and hopelessness, and thoughts of death. Also called clinical depression.
5. 1. A reduction in activity or force.
   2. A reduction in physiological vigor or activity: a depression in respiration.
   3. A lowering in amount, degree, or position.
6. Economics.
   1. A period of drastic decline in a national or international economy, characterized by decreasing business activity, falling prices, and unemployment.
   2. Depression The worldwide economic depression from the late 1920s through the 1930s. In the United States, it began with the stock market crash in October, 1929.
7. Meteorology. A region of low barometric pressure.
8. The angular distance below the horizontal plane through the point of observation.
9. Astronomy. The angular distance of a celestial body below the horizon.

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.