boom¹ / boōm/ • n. a loud, deep, resonant sound: the deep boom of the bass drum. ∎  the characteristic resonant call of the bittern.• v. [intr.] make a loud, deep, resonant sound: thunder boomed in the sky.DERIVATIVES: boom·y adj.boom² • n. a period of great prosperity or rapid economic growth: a boom in precious metal mining [as adj.] a boom economy. • v. [intr.] undergo a period of great prosperity or rapid economic growth: business is booming.boom³ • n. a long pole or rod, in particular: ∎  a spar to which a the foot of a vessel's sail is attached. ∎  [often as adj.] a movable arm over a television or movie set, carrying a microphone or camera: a boom mike. ∎  a long beam extending upward at an angle from the mast of a derrick, for guiding or supporting objects being moved or suspended. ∎  a floating beam used to contain oil spills or to form a barrier across the mouth of a harbor or river. ∎  a retractable tube for inflight transferral of fuel from a tanker airplane to another airplane.

boom1 give out a deep humming note XV; sail with great speed XVII. ult. imit. (Cf. BOMB); Cf. Du. bommen.
Hence boom sb. XVI.

boom2 (naut.) long spar; floating timber barrier. XVI (Sc. boume). — Du. boom tree, pole, BEAM.

boom3 (orig. U.S.) sudden activity in commerce. XIX. prob. application of BOOM1.
Also as vb. XIX.

boom An input device consisting of a long shaft whose end can be moved in three dimensions, so allowing three-dimensional input.