The Collaborative International Dictionary of English v.0.48:

Hushing \Hush"ing\, n. (Mining)
   The process of washing ore, or of uncovering mineral veins,
   by a heavy discharge of water from a reservoir; flushing; --
   also called booming and hydraulic mining.
   [1913 Webster +PJC]

The Collaborative International Dictionary of English v.0.48:

Booming \Boom"ing\, n.
   The act of producing a hollow or roaring sound; a violent
   rushing with heavy roar; as, the booming of the sea; a deep,
   hollow sound; as, the booming of bitterns. --Howitt.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Booming \Boom"ing\, a.
   1. Rushing with violence; swelling with a hollow sound;
      making a hollow sound or note; roaring; resounding.
      [1913 Webster]

            O'er the sea-beat ships the booming waters roar.
                                                  --Falcone.
      [1913 Webster]

   2. Advancing or increasing amid noisy excitement; as, booming
      prices; booming popularity. [Colloq. U. S.]
      [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]

WordNet (r) 3.0 (2006):

booming
    adj 1: very lively and profitable; "flourishing businesses"; "a
           palmy time for stockbrokers"; "a prosperous new
           business"; "doing a roaring trade"; "a thriving tourist
           center"; "did a thriving business in orchids" [syn:
           booming, flourishing, palmy, prospering,
           prosperous, roaring, thriving]
    2: used of the voice [syn: booming, stentorian]

Moby Thesaurus II by Grady Ward, 1.0:

101 Moby Thesaurus words for "booming":
   balmy, birring, blooming, blossoming, bombilation, bombinating,
   bombination, boom, burring, buzzing, cannonade, cannonading, clear,
   deafening, droning, ear-piercing, ear-rending, ear-splitting,
   earthshaking, echo, echoic, echoing, exuberant, fair, fat,
   flourishing, flowering, forte, fortissimo, fruiting, full,
   fulminating, going strong, growl, growling, grumble, grumbling,
   halcyon, hum, humming, in full swing, in good case, lingering,
   loud, loud-sounding, loudish, low rumbling, palmy, peal, pealing,
   persistent, piercing, piping, plangent, prospering, prosperous,
   purring, reboant, reboation, rebound, rebounding, reecho,
   reechoing, repercussive, resound, resounding, reverberant,
   reverberating, reverberation, reverberatory, ringing, roar,
   roaring, robust, roll, rolling, rosy, rumble, rumbling, sleek,
   sonorous, sounding, stentoraphonic, stentorian, stentorious,
   thrifty, thriving, thrumming, thunder, thundering, thunderlike,
   thunderous, thundery, tonitruant, tonitruous, undamped, vigorous,
   volleying, whirring, whizzing, window-rattling