From Longman Dictionary of Contemporary Englishcurveballcurve‧ball /ˈkɜːvbɔːl $ ˈkɜːrvbɒːl/ noun [countable] 1 American English in baseball, a ball that is difficult to hit because it does not move in a straight direction2 informal a surprising and unexpected action or event When life throws you a curveball, you need to know how to handle it.