WordWeb Online

1. Give sudden release to an expression
   "We burst out laughing"; "'I hate you,' she burst out"
    
2. Erupt or intensify suddenly
   "Unrest burst out in the country";
   - erupt, irrupt, flare up, flare, break open
    
3. Appear suddenly or unexpectedly; happen unexpectedly
   - crop up, pop up, pop, pop out

Derived forms: bursting out, burst out, bursts out

Type of: appear, deepen, evince [formal], express, intensify, show