What does the word mission mean?

Usage examples for mission

  1. I have sent others here on this same mission, and they did not succeed. – A Maker of History by E. Phillips Oppenheim
  2. They're away on a mission. – The Captives by Hugh Walpole
  3. It's your mission in life to be happy, and so to make others happy. – Patty's Success by Carolyn Wells