“ In the sense of a barrier, a boom is generally formed of timber lashed together, or of chains, built across the mouth of a river or harbour as a means of defence. Possibly from the metaphor of a breaking boom, and the accompanying rush and roar, or from the rush of rising waters (mingled with the onomatopoeic use) , “boom” began in America to be used of a sudden “spurt” or access of industrial activity, as in the phrase “a boom in cotton.” Hence the verb “to boom,” meaning to advertise or push into public favour. ”