An Etymological Dictionary of Astronomy and Astrophysics

A burst of very bright → ultraviolet or → soft X-ray radiation expected to occur in → core-collapse supernovae at the instant when the → supernova shock breaks out of the stellar surface. During the collapse of the progenitor → massive star,
the density in the iron core increases drastically. Once the core material reaches → nuclear density, the core rebounds generating a → shock wave that moves outward through the star.
When the shock reaches the outermost layers, it ejects them out into space at → relativistic speeds.

Etymology (EN): → shock; breakout “a forceful escape from being confined or restrained,” from break, from M.E. breken, O.E. brecan (cf. Du. breken, O.H.G. brehhan, Ger. brechen), from PIE base *bhreg- “to break” (see also → fraction) + → out.

Etymology (PE): Borunzani “emergence, evasion,” from borun, → out,

• zani verbal noun of zadan “to strike, beat,” from Mid.Pers. zatan, žatan; O.Pers./Av. jan-, gan- “to strike, hit, smite, kill” (jantar- “smiter”); cf.
  Skt. han- “to strike, beat” (hantar- “smiter, killer”);
  Gk. theinein “to strike;” L. fendere “to strike, push;” Gmc. *gundjo “war, battle;” PIE *g^when- “to strike, kill.”