paroxysm

Short definition from Wiktionary

Noun

1. 1
   A period (especially one of several recurring periods) during the course of an illness when symptoms worsen; a sudden attack of a disease symptom, such as a bout of coughing or a seizure.
2. 2
   Chiefly followed by of: a sudden outburst of violent activity or feeling; also, the most severe part of an activity or incident; the climax.
3. 3
   An outburst of a violent argument or disagreement.
4. 4
   A violent occurrence of a natural phenomenon, such as an earthquake, thunderstorm, or volcanic eruption; specifically (volcanology), the most explosive event during a series of volcanic eruptions.
5. 5
   Disastrous or sudden change.