error, mistake, fault - a wrong action attributable to bad judgment or ignorance or inattention; "he made a bad mistake"; "she was quick to point out my errors"; "I could understand his English in spite of his grammatical faults"

backfire, boomerang - a miscalculation that recoils on its maker

rounding, rounding error - (mathematics) a miscalculation that results from rounding off numbers to a convenient number of decimals; "taxes are rounded off to the nearest dollar but the rounding error is surprisingly small"

truncation error - (mathematics) a miscalculation that results from cutting off a numerical calculation before it is finished