What is the meaning of Depression?

noun

• A mental state characterized by a pessimistic sense of inadequacy and a despondent lack of activity.
• A long-term economic state characterized by unemployment and low prices and low levels of trade and investment.
  • synonyms: slump, economic crisis
• A sunken or depressed geological formation.
  • synonyms: natural depression
• Sad feelings of gloom and inadequacy.
• A period during the 1930s when there was a worldwide economic depression and mass unemployment.
  • synonyms: Great Depression
• An air mass of lower pressure; often brings precipitation.
  • usage: "a low moved in over night bringing sleet and snow"
  • synonyms: low
• A state of depression and anhedonia so severe as to require clinical intervention.
  • synonyms: depressive disorder, clinical depression
• A concavity in a surface produced by pressing.
  • usage: "he left the impression of his fingers in the soft mud"
  • synonyms: impression, imprint
• Angular distance below the horizon (especially of a celestial object. )
• Pushing down.
  • usage: "depression of the space bar on the typewriter"