Estimate
Part of speech: noun
Definition: A rough calculation or guess. A document (or verbal notification) specifying how much a job will probably cost.
Part of speech: verb
Definition: to calculate roughly, often from imperfect data
Example sentence: In an efficient market, at any point in time, the actual price of a security will be a good estimate of its intrinsic value.
Overestimate
Part of speech: verb
Definition: to judge too highly:
Example sentence: Humans are terrible at predicting the future. We really overestimate what we can do in the short term and underestimate what we can do in the long term... If we can glimpse even a couple of years into the future, even that's difficult to do.