1. One who is sent on a mission, especially one sent to do religious or charitable work in a territory or foreign country.
2. People from one culture who travel to another culture to share their religious beliefs.
3. One who attempts to persuade or convert others to a particular program, doctrine, or set of principles; a propagandist.
4. Young teachers, often from wealthy communities, who have been dispatched to an urban school system in order to *crush* the achievement gap.