depression

1. (psychology, usually uncountable) 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.Examples: "I used to suffer from depression, but now I'm mostly content with my life."; "It is that Mr. Levi's death could not be dissociated from the major depression with which he was afflicted, and that indeed his suicide proceeded directly from that illness."Synonyms: despondency, hopelessness, misery, blueness, blues, crestfallenness, dejection, depressionuncountableusually

2. (psychology, countable) 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.Examples: "[…] 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[…]"; "Many alcoholics who die from suicide suffer from deep depressions that are quite frequently protracted,[…]"countable

3. (geography) An area that is lower in topography than its surroundings.Examples: "It was not far from the house; but the ground sank into a depression there, and the ridge of it behind shut out everything except just the roof of the tallest hayrick. As one sat on the sward behind the elm, with the back turned on the rick and nothing in front but the tall elms and the oaks in the other hedge, it was quite easy to fancy it the verge of the prairie with the backwoods close by."; "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."countableuncountable

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

5. (economics) A period of major economic contraction.countableuncountable

6. (economics, US) Four consecutive quarters of negative, real GDP growth. See NBER.Examples: "The Great Depression was the worst financial event in US history."UScountableuncountable