The word "injust" means unfair or unjustifiable. There are several synonyms that can be used to replace this word. One of the most common synonyms is "unjust," which means acting or done without consideration for what is fair or right. Another synonym is "unfair," which refers to something that is not just or equitable. "Discriminatory" is another synonym that describes something that is unjustly prejudiced against a particular group or individual. Other synonyms include "inequitable," "partial," and "biased." All of these words can be used to describe actions or situations that are not fair or right.