Blow Off Meaning

(transitive) To forcibly disconnect something by use of a firearm or explosive device.

Example:   The radioactivity was released when they blew off steam from the containment vessel.
  The engine or steamer is blowing off.
  I decided to blow off the meeting and leave early.
  We've both been blowing off Peter all day: he's really boring.
  Her leg was blown off by a landmine.