WordNet (r) 3.0 (2006):

break out
    v 1: start abruptly; "After 1989, peace broke out in the former
         East Bloc" [syn: erupt, break out]
    2: begin suddenly and sometimes violently; "He broke out
       shouting"
    3: move away or escape suddenly; "The horses broke from the
       stable"; "Three inmates broke jail"; "Nobody can break out--
       this prison is high security" [syn: break, break out,
       break away]
    4: take from stowage in preparation for use
    5: become raw or open; "He broke out in hives"; "My skin breaks
       out when I eat strawberries"; "Such boils tend to recrudesce"
       [syn: erupt, recrudesce, break out]

Moby Thesaurus II by Grady Ward, 1.0:

76 Moby Thesaurus words for "break out":
   OD, arise, be born, be brought down, be felled, be struck down,
   be traumatized, become, belch, blow open, blow out, break loose,
   break through, burst forth, burst out, catch, catch cold, clear,
   collapse, come down with, come forth, come out, come to be,
   contract, crop up, cut loose, debouch, discharge, disembarrass,
   disembroil, disengage, disentangle, disgorge, disinvolve, dislodge,
   eject, emerge, eruct, erupt, exit, explode, extricate, fever,
   find vent, free, get, get out, get to be, go into shock,
   have origin, hurl forth, irrupt, issue, issue forth, leak out,
   ooze out, originate, overdose, release, rise, run a temperature,
   run out, sicken, spew, spout, spring up, take, take birth,
   take ill, take rise, tear loose, unknot, unravel, unsnarl,
   untangle, vomit