The various definitions are thus: (of a person, animal, or other living organism) grow or develop in a healthy or vigorous way, especially as the result of a particularly favorable environment."wild plants flourish on the banks of the lake"synonyms:grow, thrive, prosper, do well, burgeon, increase, multiply, proliferate; More2.(of a person) wave (something) around to attract the attention of others."“Happy New Year!” he yelled, flourishing a bottle of whiskey"synonyms:brandish, wave, shake, wield; Morenoun1.a bold or extravagant gesture or action, made especially to attract the attention of others."with a flourish, she ushered them inside"2.MUSICa fanfare played by brass instruments.
The definition which I think applies historically is "grow or develop in a healthy or vigorous way", and it can be said of a government, a certain party, a leader, a country's end of the war, etc...
