"estimate erroneously," 1778, from mis- (1) "badly, wrongly" + estimate (v.). Related: Misestimated; misestimating. As a noun by 1843 (misestimation is by 1809).
I had misestimated his determination
miserable
miserably
Miserere
miserly
misery
misestimate
misfeasance
misfield
misfire
misfit
misfortune
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