Definition of "mission"

(countable) A set of tasks that fulfills a purpose or duty; an assignment set by an employer, or by oneself.  examples

(uncountable) Religious evangelism.  examples

(in the plural, "the missions") Third World charities, particularly those which preach as well as provide aid.  examples

(countable, Catholicism) An infrequent gathering of religious believers in a parish, usually part of a larger regional event with a central theme.  examples

A number of people appointed to perform any service; a delegation; an embassy.  quotations  examples

(obsolete) Dismissal; discharge from service

A settlement or building serving as a base for missionary work.  examples

(slang, drugs) A drug run.

(transitive) To send on a mission.  examples

(intransitive) To do missionary work, proselytize.  examples