understatement

/ˌən-dər-ˈstāt-mənt/

noun

  1. a statement that represents something as smaller or less intense, or less important than it really is : a statement that understates something; also : the act of understating something or the practice of making such statements

  2. the avoidance of obvious emphasis or embellishment : an understated condition, appearance, etc.

To say that I was surprised by this outcome would be an understatement. I was completely blindsided ….

noun phrase

  1. —used of a statement that makes something seem much smaller, much less important, etc., than it really is