misestimate
1. [ verb ] judge incorrectly
Synonyms: miscalculate
Examples:

"I had misestimated his determination"

Related terms: misjudge miscalculation
2. [ verb ] (mathematics) calculate incorrectly
Synonyms: miscalculate
Examples:

"I miscalculated the number of guests at the wedding"

Related terms: calculate arithmetic
Similar spelling:   misestimation