[1] : The Collaborative International Dictionary of English v.0.48

eruption \erup"tion\, n. l. eruptio, fr. erumpere, eruptum, to
   break out; e out + rumpere, to break: cf. f. 'eruption. see
   rupture.
   1. the act of breaking out or bursting forth; as:
      a a violent throwing out of flames, lava, etc., as from
          a volcano or a fissure in the earth's crust.
      b a sudden and overwhelming hostile movement of armed
          men from one country to another. --milton.
      c a violent commotion.
          1913 webster

                all paris was quiet . . . to gather fresh
                strength for the next day's eruption. --w.
                                                  irving.
          1913 webster

   2. that which bursts forth.
      1913 webster

   3. a violent exclamation; ejaculation.
      1913 webster

            he would . . . break out into bitter and passionate
            eruditions.                           --sir h.
                                                  wotton.
      1913 webster

   4. med. the breaking out of pimples, or an efflorescence,
      as in measles, scarlatina, etc.
      1913 webster
see also:
rupture 

[2] : WordNet (r) 2.0

eruption
     n 1: the sudden occurrence of a violent discharge of steam and
          volcanic material syn: volcanic eruption
     2: symptom consisting of a breaking out and becoming visible
     3: of volcanos pouring out fumes or lava or a deposit so
        formed syn: eructation, extravasation
     4: a sudden violent spontaneous occurrence usually of some
        undesirable condition; "the outbreak of hostilities"
        syn: outbreak, irruption
     5: a sudden very loud noise syn: bang, clap, blast, loud
        noise
     6: the emergence of a tooth as it breaks through the gum
see also:
volcanic eruption eructation extravasation outbreak irruption bang 
clap blast loud noise 

[3] : Moby Thesaurus II by Grady Ward, 1.0

67 moby thesaurus words for "eruption":
   access, belch, blaze, blaze of temper, blowout, blowup,
   breaking out, burst, cascade, convulsion, cyclone, debouchment,
   diaper rash, discharge, disgorgement, dissiliency, drug rash,
   efflorescence, ejaculation, emission, eructation, explosion,
   expulsion, extravasation, fit, flare, flare-up, gale, gush, gust,
   heat rash, high words, hives, hurricane, irruption, jet,
   nettle rash, outbreak, outburst, outpour, papular rash, paroxysm,
   prickly heat, rapids, rash, rupia, rush, sally, scene, seizure,
   skin eruption, spasm, spate, spew, spout, spouting, spurt, squirt,
   storm, tempest, tornado, torrent, upheaval, urticaria,
   vaccine rash, volcan, whirlwind

Eruption >> E Words
Eruption, definition of term: Eruption
eruption_pag1.html