mission /ˈmɪʃən/ noun [C]
JOB › an important job, usually travelling somewhere: I'll be going on a fact-finding mission to Paris next week.
GROUP › an official group of people who are sent somewhere, usually to discover information about something: a trade mission
JOURNEY › an important journey which a spacecraft or military aircraft goes on
PURPOSE › someone's duty or purpose in life: Her mission in life was to help the poor.