What does DEPRESSION mean?

noun

1. a mental state characterized by a pessimistic sense of inadequacy and a despondent lack of activity
2. a long-term economic state characterized by unemployment and low prices and low levels of trade and investment
3. a sunken or depressed geological formation
4. sad feelings of gloom and inadequacy
5. an air mass of lower pressure; often brings precipitation“a low moved in over night bringing sleet and snow”
6. a state of depression and anhedonia so severe as to require clinical intervention
7. a concavity in a surface produced by pressing“he left the impression of his fingers in the soft mud”
8. angular distance below the horizon (especially of a celestial object)