flag carrier

/F L AE1 G K AE0 R IY0 ER0/
noun
  1. 1

    A person carrying a standard or flag, usually at sporting events and parades, previously on the battlefield.

  2. 2

    A transportation company, such as a shipping or airline company, that is registered in a given state

  3. 3

    A strong supporter of a cause, or perhaps the strongest and most visible supporter of said cause.

    โ€œ"Bill was the flag carrier of the movement to improve inner city education."โ€

  4. 4

    A national airline (typically having the flag, or other national insignia, on the tail)

  5. 5

    An aircraft carrier serving as a flagship

Source: https://en.wiktionary.org/wiki/flag%20carrier