an estimate which is less than the actual figure nounan estimate which is less than the actual figure ExampleThe figure of £50,000 in turnover was a considerable underestimate.verbto think that something is smaller or not as bad as it really is ExamplesThey underestimated the effects of the strike on their sales. • He underestimated the amount of time needed to finish the work. to think that something is smaller or not as bad as it really is