misunderestimation

mis- +‎ underestimation

misunderestimation (plural misunderestimations)

1. (nonstandard) An inaccurate underestimation, or an act of misunderestimating.
   • 1983, Mr. Peck, Department of Transportation and related agencies appropriations for 1984: Hearings‎, page 157:

     We find even in our own agency very significant misunderestimations of the effectiveness.

   • 2009, January 15, “Gail Collins”, in He’s Leaving. Really.‎:

     This is not the first time our president has worried about misunderestimation, so it’s fair to regard this not as a slip of the tongue, but as something the president of the United States thinks is a word.

• As with the root misunderestimate, this is usually but not always employed in jocular reference to former US President George W. Bush.