1. the quality or state of having sides or being one-sided
2. the characteristic of favoring one side over another; bias or prejudice

Examples

• The judge’s obvious sidedness in the case raised concerns about fairness.
• Her sidedness toward her hometown team was evident in every sports discussion.
• The newspaper’s sidedness became apparent in its election coverage.
• We need to avoid sidedness when evaluating the proposals.
• The teacher’s sidedness made some students feel unfairly treated.
• His sidedness in family disputes often made things worse.