boom¹/bum; buːm/ n [C] 1 a period when there is a big increase in a particular kind of activity or something is suddenly very popular 迅速增长(期); 兴起: a boom in sales 销售激增 the building boom in the 1980s 20 世纪 80 年代的建筑高峰期 2 [C,U] a time when a country's ECONOMY is very successful 经济繁荣期