The term "nemesis," rooted in the Greek goddess of vengeance, signifies a formidable adversary that enacts retribution rather than just an ordinary opponent. In this context, it implies a relationship where one party embodies the consequences of the other’s actions, representing a force that is almost insurmountable and seeks justice through its own means.

In the specified quote from Time magazine, unions have shifted their focus from traditional rivals to the European Community's Executive Commission, whom they regard as their nemesis. This reflects a shift in opposition, identifying a more potent entity that they perceive as responsible for their grievances, underscoring the sense of justice and accountability that comes with the notion of a nemesis.