overestimate overestimate /ˌoʊvɝˈɛstəˌmeɪt/

noun

1. A calculation that results in an estimate that is too high  ( overestimate , overestimation , overrating , overreckoning )
   a calculation that results in an estimate that is too high
   
2. An appraisal that is too high  ( overappraisal , overestimate , overvaluation , overestimation )
   an appraisal that is too high
   

verb

1. () Make too high an estimate of  ( overrate , overestimate )
   make too high an estimate of
    He overestimated his own powers
   He overestimated his own powers
   
2. Assign too high a value to  ( overestimate , overvalue )
   assign too high a value to
    You are overestimating the value of your old car
   You are overestimating the value of your old car