mid-15c., bomben, bummyn, "buzz, hum, drone, make a deep, hollow, continuous sound" (earliest use was in reference to bees and wasps), probably echoic of humming. The meaning "make a loud noise, roar, rumble, reverberate" is from 15c. Compare bomb. The meaning "to burst into prosperity" (of places, businesses, etc.) is by 1871, American English. Related: Boomed; booming. Boom box "large portable stereo cassette player" is attested from 1978.

"long pole," 1640s, specifically, "long spar run out from a ship" (1660s), from Scottish boun, borrowed from Dutch boom "tree, pole, beam," from a Middle Dutch word analogous to German Baum, English beam (n.). As "movable bar for a microphone or camera," 1931.

"sudden start or increase in commercial or other activity," 1873, sometimes said to be from boom (n.1) in the specific nautical meaning "a long spar run out to extend the foot of a sail" — a ship "booming" being one in full sail. But it could just as well be from boom (n.2) on the notion of "sudden burst." The verbal sense "burst into sudden activity" seems to be slightly older (1871). Boom town is from 1883. The economic cycle of boom and bust has been so called since 1937.

"loud, deep, hollow, continued sound," c. 1500, from boom (v.). Compare boondi, an Aboriginal word for waves breaking on a beach (source of Sydney's Bondi Beach), said to be imitative of the sound.

"temporary marked increase in the birth rate," coined 1941 from baby (n.) + boom (n.2); derivative baby-boomer (member of the one that began in the U.S. in 1945) is recorded by 1963 (in newspaper articles when they began to approach college age); earlier it had sometimes meant "a young kangaroo."

"small burst of activity, prosperity, etc.," 1880, from boom (n.3) + -let.

cheerleading chant, by 1924, originally (1867) an echoic phrase imitating the sound of a skyrocket flight (sis), the burst of the fireworks (boom), and the reaction of the crowd (ah).

*bheuə-, also *bheu-, Proto-Indo-European root meaning "to be, exist, grow."

It forms all or part of: Bauhaus; be; beam; Boer; bondage; boodle; boom (n.1) "long pole;" boor; booth; bound (adj.2) "ready to go;" bower; bowery; build; bumpkin; busk; bustle (v.) "be active;" byre; bylaw; Eisteddfod; Euphues; fiat; forebear; future; husband; imp; Monophysite; neighbor; neophyte; phyletic; phylo-; phylum; phylogeny; physic; physico-; physics; physio-; physique; -phyte; phyto-; symphysis.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit bhavah "becoming," bhavati "becomes, happens," bhumih "earth, world;" Greek phyein "to bring forth, make grow," phytos, phyton "a plant," physis "growth, nature," phylon "tribe, class, race," phyle "tribe, clan;" Old English beon "be, exist, come to be, become, happen;" Old Church Slavonic byti "be," Greek phu- "become," Old Irish bi'u "I am," Lithuanian būti "to be," Russian byt' "to be."

"large, triangular foresail of a ship," 1660s, gibb, of uncertain origin. Perhaps related to gibbet on the notion of a sail "hanging" from a masthead [Barnhart, OED]; and compare gib "projecting arm of a crane." Or perhaps from the nautical verb jib, jibe "shift a sail or boom to the other side" (1690s), from Dutch gijben, gijpen "turn suddenly" (of sails), which is apparently related to gijk "boom or spar of a sailing ship."

An observant sailor watching a strange vessel approach at sea judges her character by the condition of the jibs; hence cut of (one's) jib "personal appearance" (1821). Related: Jib-boom (1748). The jib in jib-door "door flush with a wall" (1792) is of uncertain origin and probably is not the same word.

"awkward country fellow," 1560s, probably from Middle Dutch bommekijn "little barrel," diminutive of boom "tree" (see beam (n.)). Apparently, though itself Dutch, it began as a derogatory reference to Dutch people as short and dumpy. The Dutch word came into English in a more literal sense in 1630s as nautical bumkin "short boom projecting from each quarter of a vessel."