magist-, master- +

1. An outstanding achievement: Such a masterpiece can be a supreme artistic or intellectual accomplishment.
2. The most outstanding work of a creative artist or craftsman: The artist's masterpieces can be seen at the local museum of art.
3. An exceptionally good piece of creative work: After years of writing novels, the author presented his last book which was an outstanding autobiography of his life, a true masterpiece.

Masterpieces can also refer to excellent movies, or brilliant performances.

1. Expert knowledge or outstanding ability: The violinist displayed great mystery in skill and technique when playing the concerto.
2. Total control over someone or something: The parents of the deceased daughter were not capable of struggling for mastery over crying loudly in front of the other people at the funeral.
3. Full command of a subject of study: Mrs. Smith spent many years in Germany and had complete mastery in understanding the language, speaking, reading, and writing in German.

1. A woman with whom a man has a usually long-term extramarital sexual relationship: In the story, Mr. Tall had a mistress for whom he provided financial support, and he hoped his wife would never know about it!
2. A woman who owns or controls something: After her husband passed away, Mrs. Smart became the mistress of her household.
3. A female teacher: Judy used the old-fashioned term to describe her mother as being the mistress of her class at school.
4. The female owner of a dog: The little Yorkshire terrier sat on the lap of its mistriss.
5. A woman who is highly skilled in a particular activity: There are a few real mistresses of mystery novels, including Agatha Christie.

1. The person who is in charge of an independent agency that is responsible for the delivery of correspondence to people and to businesses: The postmaster is accountable for making sure that mail personnel arrange for the delivery of letters and packages, and that they are actually taken to those who are supposed to receive them.
2. The person responsible for the maintenance of a website and for being the contact point for information and complaints: Brad and his wife Alice were the postmasters for several websites and responded to incoming mail promptly.
3. A computer e-mail program that distributes, forwards, and receives electronic mail: The computer had an efficient program to function as the postmaster of the electronic messages and services it was providing.

1. A man who associates with or pays for sexual relations with prostitutes or a prostitute: In the ,movie, Jack turned out to be a whoremaster who hung around questionable areas in town, mainly close to the train station.
2. Someone who consorts with whores: A whoremaster can be a lecher or pander and spends a lot of time in dubious parts of town.
3. A pimp who procures whores for customers: A whoremaster is usually a man who finds customers for a prostitute in return for a portion of the prostitute's earnings.