irruption
1. [ noun ] a sudden violent entrance; a bursting in
Examples:

"the recent irruption of bad manners"

Related terms: entrance intrude
2. [ noun ] a sudden sharp increase in the relative numbers of a population
Related terms: population_growth
3. [ noun ] a sudden violent spontaneous occurrence (usually of some undesirable condition)
Synonyms: outbreak eruption
Examples:

"the outbreak of hostilities"

Related terms: happening epidemic recrudescence erupt
Similar spelling:   irrupt
  irruptive