The Collaborative International Dictionary of English v.0.48:

Boom \Boom\, n.
   1. A hollow roar, as of waves or cannon; also, the hollow cry
      of the bittern; a booming.
      [1913 Webster]

   2. A strong and extensive advance, with more or less noisy
      excitement; -- applied colloquially or humorously to
      market prices, the demand for stocks or commodities and to
      political chances of aspirants to office; as, a boom in
      the stock market; a boom in coffee. [Colloq. U. S.]
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Boom \Boom\, v. t.
   To cause to advance rapidly in price; as, to boom railroad or
   mining shares; to create a "boom" for; as to boom Mr. C. for
   senator. [Colloq. U. S.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Boom \Boom\ (b[=oo]m), v. t. (Naut.)
   To extend, or push, with a boom or pole; as, to boom out a
   sail; to boom off a boat.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Boom \Boom\ (b[=oo]m), v. i. [imp. & p. p. Boomed, p. pr. &
   vb. n. Booming.] [Of imitative origin; cf. OE. bommen to
   hum, D. bommen to drum, sound as an empty barrel, also W.
   bwmp a hollow sound; aderyn y bwmp, the bird of the hollow
   sound, i. e., the bittern. Cf. Bum, Bump, v. i., Bomb,
   v. i.]
   1. To cry with a hollow note; to make a hollow sound, as the
      bittern, and some insects.
      [1913 Webster]

            At eve the beetle boometh
            Athwart the thicket lone.             --Tennyson.
      [1913 Webster]

   2. To make a hollow sound, as of waves or cannon.
      [1913 Webster]

            Alarm guns booming through the night air. --W.
                                                  Irving.
      [1913 Webster]

   3. To rush with violence and noise, as a ship under a press
      of sail, before a free wind.
      [1913 Webster]

            She comes booming down before it.     --Totten.
      [1913 Webster]

   4. To have a rapid growth in market value or in popular
      favor; to go on rushingly.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Boom \Boom\ (b[=oo]m), n. [D. boom tree, pole, beam, bar. See
   Beam.]
   1. (Naut.) A long pole or spar, run out for the purpose of
      extending the bottom of a particular sail; as, the jib
      boom, the studding-sail boom, etc.
      [1913 Webster]

   2. (Mech.) A long spar or beam, projecting from the mast of a
      derrick, from the outer end of which the body to be lifted
      is suspended.
      [1913 Webster]

   3. A pole with a conspicuous top, set up to mark the channel
      in a river or harbor. [Obs.]
      [1913 Webster]

   4. (Mil. & Naval) A strong chain cable, or line of spars
      bound together, extended across a river or the mouth of a
      harbor, to obstruct navigation or passage.
      [1913 Webster]

   5. (Lumbering) A line of connected floating timbers stretched
      across a river, or inclosing an area of water, to keep saw
      logs, etc., from floating away.
      [1913 Webster]

   Boom iron, one of the iron rings on the yards through which
      the studding-sail booms traverse.

   The booms, that space on the upper deck of a ship between
      the foremast and mainmast, where the boats, spare spars,
      etc., are stowed. --Totten.
      [1913 Webster]

WordNet (r) 3.0 (2006):

boom
    n 1: a deep prolonged loud noise [syn: boom, roar,
         roaring, thunder]
    2: a state of economic prosperity
    3: a sudden happening that brings good fortune (as a sudden
       opportunity to make money); "the demand for testing has
       created a boom for those unregulated laboratories where boxes
       of specimen jars are processed like an assembly line" [syn:
       boom, bonanza, gold rush, gravy, godsend, manna
       from heaven, windfall, bunce]
    4: a pole carrying an overhead microphone projected over a film
       or tv set [syn: boom, microphone boom]
    5: any of various more-or-less horizontal spars or poles used to
       extend the foot of a sail or for handling cargo or in mooring
    v 1: make a resonant sound, like artillery; "His deep voice
         boomed through the hall" [syn: boom, din]
    2: hit hard; "He smashed a 3-run homer" [syn: smash, nail,
       boom, blast]
    3: be the case that thunder is being heard; "Whenever it
       thunders, my dog crawls under the bed" [syn: thunder,
       boom]
    4: make a deep hollow sound; "Her voice booms out the words of
       the song" [syn: boom, boom out]
    5: grow vigorously; "The deer population in this town is
       thriving"; "business is booming" [syn: boom, thrive,
       flourish, expand]

Moby Thesaurus II by Grady Ward, 1.0:

381 Moby Thesaurus words for "boom":
   Carling float, access, accession, accretion, accrual, accrue,
   accruement, accumulate, accumulation, addition, advance,
   aggrandizement, amplification, appreciate, appreciation, arch dam,
   ascent, augmentation, awake the dead, backfire, backstop,
   ball the jack, balloon, ballooning, balsa, balsa raft,
   bamboo curtain, bang, bank, bar, bark, barrage, barrel, barrier,
   batten, bawl, be reflected, be sent back, beam, bear-trap dam,
   beaver dam, bellow, birr, blare, blast, blast the ear, blat, bloat,
   bloating, bloom, blossom, blowout, blowup, blubber, board, bob,
   bombilate, bombinate, boom, booming, booming economy, boost,
   bottoming out, bounce back, bowl along, bray, breakwater,
   breastwork, breathe, breed, breeze, breeze along, brick wall,
   broaden, broadening, brush, buffer, buildup, bulkhead, bull market,
   bulwark, bum, buoy, burgeon, burgeoning, burr, burst,
   business cycle, business fluctuations, bust, buzz, cackle,
   cannonade, cant hook, cast loose, chant, chirp, clap,
   clap on ratlines, claw bar, clear hawse, clip, cofferdam, coo,
   cooling off, cork, crack, crank, crash, crescendo, crisis, crow,
   crowbar, cut along, cut loose, dam, deafen, defense, depression,
   detonation, develop, development, dike, din, discharge, ditch,
   downturn, drawl, drone, earthwork, echo, echo back, economic cycle,
   economic expansion, economic growth, edema, elevation, embankment,
   enlargement, exclaim, expanding economy, expansion, explode,
   explosion, extension, fatten, fence, fill the air, flare, flash,
   fleet, flit, float, flood, flourish, flower, flute, fly, fly low,
   foot, fulguration, fulmination, gain, gain strength, gasp, gate,
   get ahead, go fast, go up, gravity dam, greatening, groin, grow,
   grow fat, growl, growling, growth, grumble, grumbling, grunt, gush,
   handspike, haul, haul down, heave, heave apeak, heave round,
   heave short, high growth rate, highball, hike, hiss, hum,
   hydraulic-fill dam, increase, increment, inflation, intensify,
   iron crow, iron curtain, jam, jetty, jimmy, jump, kedge, keen,
   land-office business, lay, lay aloft, leap, leaping weir, levee,
   lever, life buoy, life preserver, life raft, lilt, limb, log,
   logjam, low, make knots, market expansion, marlinespike, milldam,
   moat, mole, mound, mount, mounting, multiplication, multiply,
   mumble, murmur, mutter, nip, outrigger, outstrip the wind, pant,
   parapet, peak, peaking, peal, peavey, pedal, pinch bar, pipe,
   pontoon, portcullis, pour it on, prize, productiveness,
   profitability, progress, proliferate, proliferation, prosper,
   prosperity, prosperousness, pry, purr, raft, raise, rampart,
   ratline down, rattle the windows, reboation, rebound, recession,
   recovery, reecho, rend the air, rend the ears, report, resonate,
   resound, resounding, return, reverberate, reverberation, ring, rip,
   ripping bar, rise, roadblock, roar, roaring trade, rock the sky,
   rock-fill dam, roll, rumble, rumbling, run up, scorch, scream,
   screech, seawall, send back, shoot up, shriek, shutter dam,
   sibilate, sigh, sing, sizzle, skim, slam, slowdown, slump, smash,
   snap, snarl, snort, snowball, snowballing, sob, sound, spar,
   spar down, speed, split the eardrums, split the ears, spread,
   squall, squawk, squeal, startle the echoes, stone wall,
   storm along, stream the log, strengthen, stun, surfboard, surge,
   sweep, swell, swelling, tear, tear along, thrive, thrum, thunder,
   thunder along, thundering, traverse a yard, treadle, trumpet,
   tumescence, twang, unlash, up, upping, upsurge, upswing, uptrend,
   upturn, wail, wall, warble, warp, wax, waxing, weir, wham, whine,
   whir, whisk, whisper, whiz, wicket dam, widen, widening, work,
   wrecking bar, yap, yawp, yell, yelp, zing, zip, zoom