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]

Moby Thesaurus II by Grady Ward, 1.0:

37 Moby Thesaurus words for "firecracker":
   Klaxon, Roman candle, boiler factory, boiler room, bomb,
   bull-roarer, cap, catcall, cherry bomb, clack, clacker, clapper,
   cracker, cricket, flare, flowerpot, girandole, horn, ladyfinger,
   noisemaker, pinwheel, rattle, rattlebox, rocket, serpent, siren,
   skyrocket, snake, snapper, sparkler, squib, steam whistle,
   ticktack, torpedo, whistle, whizgig, whizzer