Prejudice is an unreasonable dislike of a particular group of people or things, or a preference for one group of people or things over another.

If you prejudice someone or something, you influence them so that they are unfair in some way.

If someone prejudices another person's situation, they do something which makes it worse than it should be.

If you take an action without prejudice to an existing situation, your action does not change or harm that situation.