definition of
irruption

[1] #1 irruption n. a sudden violent entrance; a bursting in; "the recent irruption of bad manners". wn

[2] #2 irruption n. a sudden sharp increase in the relative numbers of a population. wn

[3] #3 irruption n. [outbreak, eruption] a sudden violent spontaneous occurrence (usually of some undesirable condition); "the outbreak of hostilities". wn