roll·back /ˈrəʊlbæk $ ˈroʊl-/ noun [countableC, uncountableU] especially American EnglishAmE
an occasion when a tax, price, law etc is reduced to a previous level or changed so that it is the way it used to be 〔税收、价格等的〕回调,回落;〔法律的〕回复,恢复 → roll backat roll1