The Collaborative International Dictionary of English v.0.48:

Blow-out \Blow"-out`\, n.
   The cleaning of the flues of a boiler from scale, etc., by a
   blast of steam.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

blowout \blowout\ n.
   1. a gay or lavish festivity. [colloq.]

   Syn: gala, gala affair, jamboree.
        [WordNet 1.5]

   2. the sudden deflation of an inflatable tire due to a
      puncture or rupture, often accompanied by a bang.
      [PJC]

   3. the sudden escape of gas or liquid confined under
      pressure, such as in a gas or oil well, or in a system
      containing pressurized air or steam.
      [PJC]