What is an unfair opinion not based on fact?

An unfair opinion not based on fact is known as a prejudice. Prejudices are preconceived judgments or attitudes towards a person or group that are not based on actual experience or knowledge. These opinions are often rooted in stereotypes, bias, or misinformation, rather than objective evidence or rational reasoning. It is important to challenge and address prejudices in order to promote understanding, empathy, and equality.