To mistakenly underestimate. Means that you misunderstood something so poorly that you completely underestimated it, realizing later that it was a dire, but likely preventable (had you fully understood the situation), mistake.
I misunderestimated my teacher's desire to fail me in math.
by jsday187 January 04, 2011
A word made up by one of the biggest fucking idiots this world has ever seen.
G.W. Bush's wife misunderestimated the size of my load, and choked and died.
by j valentine August 24, 2007
a word made up by jenna pisarev. or george bush. further inquiries will follow.
midterms are so expensive! i always misunderestimate.....
by your love. February 21, 2009