An inaccurate underestimation, or an act of misunderestimating.(noun)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "misunderestimation" in a sentence
"If these individuals are indeed wounded, it is more likely an understated wounded pride at their "misunderestimation" -- that such a receptive servant of the message, no doubt hired for his unquestioning fealty, would now actually remove the curtain from the proceedings that they expected that he would obediently continue to conceal."
"I've been engaged as a volunteer advocate and political hobbyist but I'm growing tired and expect that little of substance will survive the Senate and conference, largely due to Obama's overreaching and "misunderestimation" of the opposition to disguised spending we cannot afford."
"This is more of the same "misunderestimation" of one's opponents which cause bureaucrats like Powell to lose consistently to Cheney."