The Collaborative International Dictionary of English v.0.48:

blitz \blitz\ n.
   1. (football) a quick move by defensive players toward the
      passer on the offensive team, as soon as the ball is
      snapped; -- it is used when the defensive teams assumes
      that a pass will be attempted, and risks allowing
      substantial gains by the offensive team if other plays are
      in fact planned.

   Syn: safety linebacker blitzing.
        [WordNet 1.5 +PJC]

   2. a rapid and violent military attack with intensive aerial
      bombardment. Same as blitzkrieg
      [WordNet 1.5]

   3. any vigorous and intensive attack, bombardment, or
      assault, literally or figuratively; as, they used a blitz
      of television commercials to launch their new product; the
      German blitz on London.
      [WordNet 1.5 +PJC]

   3. same as blitz chess.
      [PJC]

WordNet (r) 3.0 (2006):

blitz
    n 1: (American football) defensive players try to break through
         the offensive line [syn: safety blitz, linebacker
         blitzing, blitz]
    2: a swift and violent military offensive with intensive aerial
       bombardment [syn: blitz, blitzkrieg]
    v 1: attack suddenly and without warning; "Hitler blitzed
         Poland"