Meaning

1. A master, boss, superior.
2. A schoolteacher, notably in primary education.
3. A manager, person put in charge of something.
4. An expert or champion in something.
5. A holder of an academic master degree, especially in law.
6. Form of address for an attorney.
7. A slave's or serf's owner.
8. A title or rank in certain organisations, such as guilds or lodges.
9. A train driver.