What is the meaning of downcast?

noun

• A ventilation shaft through which air enters a mine.

adjective

• Directed downward.
  • usage: "a downcast glance"
• Filled with melancholy and despondency .
  • usage: "gloomy at the thought of what he had to face"; "gloomy predictions"; "a gloomy silence"; "took a grim view of the economy"; "the darkening mood"; "lonely and blue in a strange city"; "depressed by the loss of his job"; "a dispirited and resigned expression on her face"; "downcast after his defeat"; "feeling discouraged and downhearted"
  • synonyms: gloomy, grim, blue, depressed, dispirited, down, downhearted, down in the mouth, low, low-spirited