master or boss, used originally by servants to address their owners

a person who pulls the strings or controls others from a position of leadership, often used with a negative or mocking tone

(literary) a person of a certain type or character, usually used sarcastically to describe someone's behavior or personality

(archaic) a customer or client; a reliable person to do business with

the operator or controller of a machine or piece of equipment

the emperor, as addressed by his subjects or subordinates