runawayrun·a·way /ˈrʌnəweɪ/ adjectiveadj1runaway costs/prices/ inflation etcECONOMICS costs, prices etc that are increasing uncontrollablythe runaway costs of workers’ compensation
Bolivia was experiencing runaway inflation and foreign debt.
2a runaway success/hit/bestseller etc an extremely successful product, book, film etcThe game has been a runaway bestseller.