This is the 15375th most frequent German word.
vereinigte
"Vereinigte" means "united" in English.
Here, 'vereinigte' is an adjectival use describing the workers as united (coming together for a common cause).
Die Arbeiter haben sich zu einer Gewerkschaft zusammengeschlossen und sind nun vereinigte Kräfte.
The workers have come together to form a union and are now united forces.
In this use, 'vereinigten' as an adjective depicts the aspiration for a unity among European nations.
Europa träumt von einer zukünftigen vereinigten Gemeinschaft.
Europe dreams of a future united community.
In this sentence, 'Vereinigte' (United) is used as part of a proper noun, describing the unity of the states.