prejudicial

If something is prejudicial, it's unfairly biased or damaging. If you've already decided that you don't like your new biology teacher before you've even met her, you're treating her in a prejudicial way.

While prejudicial can be used as a synonym for prejudiced or biased, it's more commonly used to simply mean "damaging." A child's temper tantrum is prejudicial to the teacher's control of a preschool class. And a negative opinion piece in the newspaper about a local car dealer might be prejudicial to its business — in other words, it might hurt car sales. The Medieval Latin root is prejudicialis, "injurious."

Definitions of prejudicial
  1. adjective
    tending to favor preconceived ideas
    synonyms: prejudicious
  2. adjective
    (sometimes followed by 'to') causing harm or injury
    “the reporter's coverage resulted in prejudicial publicity for the defendant”
    synonyms: damaging, detrimental, prejudicious
    harmful
    causing or capable of causing harm
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