flag carrier

Meanings

1. A person carrying a standard or flag, usually at sporting events and parades, previously on the battlefield.
2. A strong supporter of a cause, or perhaps the strongest and most visible supporter of said cause.
3. A transportation company, such as a shipping or airline company, that is registered in a given state.
4. A national airline (typically having the flag, or other national insignia, on the tail).
5. An aircraft carrier serving as a flagship.