baby boomEnglishOxford New American Dictionarybaby boom /ˈbābē ˌbo͞om, ˈbeɪbi ˌbum / ▸ noun informal a temporary marked increase in the birth rate, especially the one following World War II: the number of college graduates mushroomed in the early- to mid-1970s, thanks to the baby boom [as modifier] the baby boom generation.