Shakespeare employs a rhetorical technique called antimony to emphasize events or situations or to emphasize characters' thoughts or feelings. An antinomy is similar to a paradox. An antinomy presents two principles that are needed for a conclusion yet contradict each other, thus setting up a paradox. [A paradox presents two truths that seem to contradict each other but that may each actually be true.]
Shakespeare sets up this contradictory characteristic element of antinomy in Othello from the very beginning. When Iago is talking to Roderigo in Act I, scene i, he speaks of Brabantio in terms of an antinomy. Iago says:
Call up her father,
Rouse him: make after him, poison his delight,
The antimony is the phrase "poison his delight." The contradiction lies in the logical inability to apply poison to an emotion or a sentimental response. This antimony means that the news Iago and Roderigo intend to deliver to Brabantio, Desdemona's father, will give him a devastating psychological shock that will make him feel anything but delight.
Another antimony is this one, also with synaesthesia imagery, that also is spoken by Iago about Brabantio,
though that his joy be joy,
Yet throw such changes of vexation on't,
As it may lose some colour.
In this antinomy, which is similar in meaning to the first, Iago suggests that he and Roderigo give Brabantio such bad news that his joy be changed by vexation to sorrow. It is a contradiction in principles and a logical paradox that joy can lose "colour," which also represents the synaesthesia: an emotion losing a visible element. [As an aside, antinomy is a term usually reserved for philosophy, as in Immanuel Kant's philosophy. It is not often used in reference to literature. The more common term for literature is paradox.]