Meaning of “overestimate” - Learner’s Dictionary

overestimate

verb [ I, T ] uk us /ˌəʊvərˈestɪmeɪt/

to guess or think that something is bigger or better than it really is:

They overestimated her ability to do the job.
→ Opposite underestimate

(Definition of “overestimate” from the Cambridge Learner’s Dictionary © Cambridge University Press)