Definition from Wiktionary, the free dictionary
flagship (plural flagships)
- In a maritime fleet, the ship occupied by the fleet's commander (usually an admiral); it denotes this by flying his flag.
- The most important one out of a related group.
- The retail company's store in London is their flagship.
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.
ship occupied by the fleet's commander