a calculation made without any real information nouna calculation made without any real information ExampleThe forecast of sales is only a guess.Usagean informed guessa guess which is based on some informationUsageit is anyone's guessno one really knows what is the right answerverbUsageto guess (at) somethingto try to calculate something without any information ExamplesThey could only guess at the total loss. • The sales director tried to guess the turnover of the Far East division.