‘Bias’ means a treating people or groups unfairly because you have a conscious or unconscious belief that some people or ideas are better than others. You’ll often see the phrases ‘racial bias’ and ‘gender bias’ these days.
‘Biased’ is the adjective form of the word.
“The manager was accused of gender bias because he gave the best projects to the male employees."
"The female employees accused him of being biased against women.”
Bias is an unfair preference of one thing over the other. It is characterized by favouritism and a subjective opinion.
"Despite the bias of the referee during the match, Arsenal later won."
Biased means to exhibit or display the characteristics of bias. It could also mean the tendency to yield an outcome repeatedly in a statistical experiment.
"He is just too biased against the female gender."