One that has control over another person, a group of persons, or a thing, especially, A man who acts out the role of the dominating partner in a sadomasochistic relationship, An original, such as an original document or audio recording, from which copies can be made, adjective_ Being an original from which copies are made, Controlling all other parts of a mechanism, transitive verb_ To become very skilled in or knowledgeable about, To produce a master copy of (an audio or video recording, for example)