From Middle English *outbersten, *outbresten, *outbrasten, equivalent to out- + burst.
outburst (third-person singular simple present outbursts, present participle outbursting, simple past outburst or outbrast, past participle outburst or outbursten)
- (intransitive) To burst out.
outburst (plural outbursts)
- a sudden, violent expression of emotion or activity
- The man let out an outburst of invective
a sudden expression of emotion