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]