A key designed to open a set of several locks; a passkey. / (figuratively) Any tool or technique that can solve many types of difficulty.

A room in a house, in which the head of the household sleeps, typically larger and better furnished than other bedrooms.

A skilled and experienced tradesman, especially one who has submitted a masterpiece to his guild.

(humorous) Respectful term of address for an expert in a particular field.

A postgraduate degree usually in a non-science subject. / A person holding such a degree.

(film) A master shot in which the camera moves relative to the performance.

(UK, historical) A keeper of a livery stable who lets (rents) out horses and carriages by the week or month.

In Chinese cooking, a stock which is repeatedly reused to poach or braise meats.

plural of master stock

A person who entertains with, or operates puppets; a puppeteer. / (figuratively, by extension) A person who controls other people and/or events.