preconceived
v. C1 Advanced US //ˌpɹikənˈsivd// UK //pɹˌiːkənsˈiːvd// pre·con·ceived
v. already formed in your mind before you have any real experience or information. You use this to describe an opinion or idea that you cannot change because you already believe it.
v. formed or held in advance of experience or evidence. Often used to describe biases or assumptions that prevent a person from considering new information objectively.
He had preconceived ideas about the city before he arrived.
The manager's preconceived notions about the team's performance made it difficult for him to accept the new data.
To overcome a preconceived bias, one must actively seek out information that contradicts their existing beliefs and remain open to the possibility of being proven wrong.