misassumption
/ˌmɪsəˈsʌmpʃən/
noun
- A wrong or incorrect belief that something is true without having all the facts.
- Many conflicts arise from a simple misassumption about someone's intentions.
- Her misassumption that the meeting was canceled caused her to miss an important presentation.
- The whole argument was based on a misassumption about the project's budget.
Antonyms