(bm) noun
1. Naut. A spar holding the foot of a fore-and-aft sail, or that attached to a yard or to another boom to extend it.
2. A chain of logs to intercept or retard the advance of a vessel, to confine timbers, sawlogs, etc.
3. A pole set up to mark a navigable channel.
4. A long mobile beam projecting from the foot of a derrick to carry a load raised from its outer end.
—to lower the boom Slang To act decisively to correct abuses; crack down.
—v.t.
1. To extend (a sail) by means of a boom: with out.
2. To shove off or away, as a vessel from a wharf: with off.
3. To equip (a river, lake, etc.) with a barrier to stop floating logs. [<Du. boom tree, beam. Akin to BEAM.]

(bm) v.i.
1. To emit a deep, resonant sound, as cannon or drums.
2. To hum loudly, as bees.
3. To rush swiftly or in tumult.
4. To grow rapidly; flourish.
—v.t.
5. To utter or sound in a deep resonant tone: to boom the hour.
6. To extol; praise or advertise vigorously.
7. To cause to flourish: Prosperous times boomed my business.
8. To rush, as logs, down a river.
—noun
1. A deep, reverberating sound, as of a supersonic aircraft, waves, etc.
2. Any sudden or rapid growth or popularity. [Imit. Cf. G bummen hum, Gk. bombos hollow noise.]