Unbiased means not favoring one side over another, making judgments based only on facts and evidence rather than personal preferences or prejudices. When a referee is unbiased, she calls fouls the same way for both teams, even if one team is her daughter's favorite. When a teacher grades papers in an unbiased way, he judges each essay by the same standards, not by which students he likes best.

Being unbiased is especially important for people in positions of authority or trust: judges, journalists, scientists, and umpires all need to set aside their personal feelings and look at situations fairly. A scientist running an experiment should be unbiased, recording results accurately whether or not they support her hypothesis. A journalist writing a news story should present different viewpoints without letting her own opinions color the facts.

The opposite is biased, which means unfairly favoring one side. Everyone has natural biases (we all have preferences and opinions), but being unbiased means recognizing those feelings and not letting them affect your decisions or judgments. When your older brother volunteers to split the last cookie between you and your sister, you might reasonably question whether he can be truly unbiased about it.