In Act 1, Scene 2, the audience is introduced to Claudius, the new king of Denmark, who has recently married Hamlet’s mother. In his opening monologue, Claudius remembers his brother, the former king, whose recent death hangs over the beginning of the play. After expanding upon the importance of mourning his brother, he encourages the kingdom and its subjects to move on with their lives. As he does so, he uses an oxymoron:
[...] (as ‘twere with a defeated joy,
With an auspicious and a dropping eye,
With mirth in funeral and with dirge in marriage,
In equal scale weighing delight and dole)
Claudius describes his sadness and his joy as one emotion and says that he cries from one eye and expresses his happiness with the other. The phrases he uses in this speech are purposefully oxymoronic, and the context for his situation becomes important to decipher his intentions and his emotional state. These lines grow in importance because they are some of Claudius’s first: they shape the audience’s impression of him.
There is some playfulness in Claudius's language and in the way he builds contradictory phrases about his mix of emotions. Using a phrase like "defeated joy" makes it clear that there is an inherent tension in what Claudius is advising others to pursue. He is telling them to do two things at once, ignoring the fact that it is impossible to be defeated and joyful at the same time. The source of this tension becomes clear later in the play. Claudius advocates that the kingdom move on and falsifies his grief because of the tension in his situation. He has become king and gotten all of the power that he wanted, but has done so through murder and immorality. His use of oxymoron in this scene therefore allows him to express that tension within the language itself, allowing the audience to detect the duplicity of his character before his crimes are even revealed.