1) Military terminology 
A flag officer is a commissioned officer in a nation`s armed forces senior enough to be entitled to fly a flag to mark the position from which the officer exercises command. The term is used differently in different countries: ==General usage== The generic title of flag officer is used in several modern navies and coast guards to denote those who....
[n] - a senior naval officer above the rank of captain
a naval officer above the rank of captain, as a fleet admiral, admiral, vice-admiral, rear admiral, or commodore, who is entitled to display a flag indicating his or her rank. · (formerly) an officer in command of a fleet, squadron, or group of ships.