The Collaborative International Dictionary of English v.0.48:

Blundering \Blun"der*ing\, a.
   Characterized by blunders.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Blunder \Blun"der\, v. i. [imp. & p. p. Blundered; p. pr. &
   vb. n. Blundering.] [OE. blunderen, blondren, to stir,
   confuse, blunder; perh. allied to blend to mix, to confound
   by mixture.]
   1. To make a gross error or mistake; as, to blunder in
      writing or preparing a medical prescription. --Swift.
      [1913 Webster]

   2. To move in an awkward, clumsy manner; to flounder and
      stumble.
      [1913 Webster]

            I was never distinguished for address, and have
            often even blundered in making my bow. --Goldsmith.
      [1913 Webster]

            Yet knows not how to find the uncertain place,
            And blunders on, and staggers every pace. --Dryden.
      [1913 Webster]

   To blunder on.
      (a) To continue blundering.
      (b) To find or reach as if by an accident involving more
          or less stupidity, -- applied to something desirable;
          as, to blunder on a useful discovery.
          [1913 Webster]