The Collaborative International Dictionary of English v.0.48:

Cracker \Crack"er\ (kr[a^]k"[~e]r), n.
   1. One who, or that which, cracks.
      [1913 Webster]

   2. A noisy boaster; a swaggering fellow. [Obs.]
      [1913 Webster]

            What cracker is this same that deafs our ears?
                                                  --Shak.
      [1913 Webster]

   3. A small firework, consisting of a little powder inclosed
      in a thick paper cylinder with a fuse, and exploding with
      a sharp noise; -- usually called firecracker.
      [1913 Webster]

   4. A thin, dry biscuit, often hard or crisp; as, a Boston
      cracker; a Graham cracker; a soda cracker; an oyster
      cracker.
      [1913 Webster]

   5. A nickname to designate a poor white in some parts of the
      Southern United States. --Bartlett.
      [1913 Webster]

   6. (Zool.) The pintail duck.
      [1913 Webster]

   7. pl. (Mach.) A pair of fluted rolls for grinding
      caoutchouc. --Knight.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

firecracker \fire"crack`er\, n.
   A small explosive device consisting of a paper or cardboard
   cylinder having only sufficient explosive mixture to make a
   loud bang, ignited by a short fuse, and used mostly as an
   entertainment or in celebrations. Same as Cracker., n., 3.
   [1913 Webster +PJC]

WordNet (r) 3.0 (2006):

firecracker
    n 1: firework consisting of a small explosive charge and fuse in
         a heavy paper casing [syn: firecracker, cracker,
         banger]