\E*rup"tion\, n. [L. eruptio, fr. erumpere, eruptum, to
break out; e out + rumpere, to break: cf. F. ['e]ruption. 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 of 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.
             All Paris was quiet . . . to gather fresh
             strength for the next day's eruption. --W.
                                               Irving.
2. That which bursts forth.
3. A violent exclamation; ejaculation.
         He would . . . break out into bitter and passionate
         eruditions.                           --Sir H.
                                               Wotton.
4. (Med.) The breaking out of pimples, or an efflorescence,
   as in measles, scarlatina, etc.