a guess that is too high or too big, or the act of making such a guess

The reporting error led to an over-estimation of the number of cases of the disease.

Overestimation of damage is common with insurance claims. 高估损失在保险索赔中很常见。

a judgment that something is better or more important than it really is

They admitted an initial overestimation of the benefits of the scheme.

She suffers from a poor understanding of the game combined with an over-estimation of her own ability. 她对比赛的了解不足，加上对自己能力的高估，因此蒙受损失。