The most important one out of a related group.
The ship occupied by the fleet's commander (usually an admiral); it denotes this by flying his flag.
The ship regarded as most important out of a group, e.g. a nation's navy or company's fleet.
To act as a flagship for.
A powerful polity or institution.
A self-important person.
A powerful leader; a monarch; a ruler.
Someone acting in an important role.