The Collaborative International Dictionary of English v.0.48:

Scribble \Scrib"ble\, v. t. [imp. & p. p. Scribbled (-b'ld);
   p. pr. & vb. n. Scribbling (-bl[i^]ng).] [From Scribe.]
   1. To write hastily or carelessly, without regard to
      correctness or elegance; as, to scribble a letter.
      [1913 Webster]

   2. To fill or cover with careless or worthless writing.
      [1913 Webster]