Master:
1. a person with the ability or power to use, control, or dispose of something: a master of six languages; to be master of one's fate.
2. an owner of a slave, animal, etc.
3. an employer of workers or servants.
4. the male head of a household.
5. a person eminently skilled in something, as an occupation, art, or science: the great masters of the Impressionist period.