- the ship that carries the commander of a fleet or other large naval unit and displays his flag
- the finest, largest, or newest ship of a steamship line
- the finest, largest, or most important member or part as of a group or a broadcast network
- A ship that carries a fleet or squadron commander and bears the commander's flag.
- The chief one of a related group: the flagship of a newspaper chain.
The word flagship is often used as an attributive noun, as in:
- The company’s shop in London is their flagship store.
Although this usage looks like an adjective, it is not, and should not be confused with that part of speech.