D defs.my
Entry 1 sense Webster, 1913

Upburst

· Up·burst · IPA
01 n. The act of bursting upwards; a breaking through to the surface; an upbreak or uprush; as, an upburst of molten matter.
  1. 1.
    The act of bursting upwards; a breaking through to the surface; an upbreak or uprush; as, an upburst of molten matter.