Preconception (noun)

1. An idea or opinion that is formed before having enough information or experience to form a valid judgement.
2. A prejudice or bias held before having actual knowledge or experience of the matter.

Origin:

From preconceive + -ion.

Examples:

1. He had a preconception that the new product would be a failure.
2. Her preconception about the class made her miss out on a valuable learning experience.
3. The preconception that women are bad drivers is not based on any evidence.
4. The preconception that the new employee would be difficult to work with proved to be unfounded.
5. The preconception that the candidate would not be suitable for the job was proved to be wrong after the interview.