depression

A state of mind producing serious, long-term lowering of enjoyment of life or inability to visualize a happy future; any of several mental disorders with this state of mind as a central feature.uncountableusually

• I used to suffer from depression, but now I'm mostly content with my life.

A period of low morale or unhappiness (a period of experiencing the above-mentioned state of mind) which lasts longer than several weeks and may include ideation of self-inflicted injury or suicide.countable

• […] your illness reflects the textbook description of bipolar disorder (euphoric, grandiose, manic highs followed by deep depressions,[…]
• His first major breakdown occurred when his son was five years old; he continued to go to pieces periodically, with a particularly deep depression that lasted from the time Bill was in sixth grade until the time he finished junior high[…]

An area that is lower in topography than its surroundings.countableuncountable

• These large [mazes] led to smaller ones which were constructed to hold in the hand, usually in the form of a circular tray. In these a marble was contained which had to be manipulated to roll into a depression in the centre.

An area of lowered air pressure that generally brings moist weather, sometimes promoting hurricanes and tornadoes.countableuncountable

A period of major economic contraction.countableuncountable

A period of major economic contraction.; Four consecutive quarters of negative, real GDP growth (for example, this operational definition is used by the US NBER and many other writers).countableuncountable

• The Great Depression was the worst financial event in US history.

The act of lowering or pressing something down.countableuncountable

• Depression of the lever starts the machine.

A lowering, in particular a reduction in a particular biological variable or the function of an organ, in contrast to elevation.countableuncountable