Step 1: Meaning of “justice.”
Justice refers to fairness, equality, and moral rightness.
Step 2: Find the opposite.
- “Injustice” means lack of justice or unfair treatment. This is the correct antonym.
- “Unjustice” is not a standard English word.
- “Malpractice” refers to professional negligence, not directly the opposite of justice.
- “Malice” means ill will or desire to harm others, not opposite of justice.
Step 3: Conclusion.
Therefore, the antonym of “justice” is “injustice.”
Final Answer:
\[
\boxed{\text{injustice}}
\]