n.
Function: noun
Date: 15th century
1 : a booming sound or cry ― often used interjectionally to indicate suddenness <then boom , he was fired>
2 : a rapid expansion or increase: as a : a general movement in support of a candidate for office b : rapid settlement and development of a town or district c : a rapid widespread expansion of economic activity d : an upsurge in activity, interest, or popularity <a folk music boom >