rollover
noun [ C ] uk/ˈrəʊl.əʊ.vər/ us/ˈroʊl.oʊ.vɚ/
（比赛或彩票奖金由于没人获得而累计入下一期的）累积，滚动增加
a situation in which a prize has not been won in a competition and is added to the prize offered in the next competition
a rollover week 奖金累积滚入下一期的一周