The Collaborative International Dictionary of English v.0.48:

Forge \Forge\, v. t. [imp. & p. p. Forged; p. pr. & vb. n.
   Forging.] [F. forger, OF. forgier, fr. L. fabricare,
   fabricari, to form, frame, fashion, from fabrica. See
   Forge, n., and cf. Fabricate.]
   1. To form by heating and hammering; to beat into any
      particular shape, as a metal.
      [1913 Webster]

            Mars's armor forged for proof eterne. --Shak.
      [1913 Webster]

   2. To form or shape out in any way; to produce; to frame; to
      invent.
      [1913 Webster]

            Those names that the schools forged, and put into
            the mouth of scholars, could never get admittance
            into common use.                      --Locke.
      [1913 Webster]

            Do forge a life-long trouble for ourselves.
                                                  --Tennyson.
      [1913 Webster]

   3. To coin. [Obs.] --Chaucer.
      [1913 Webster]

   4. To make falsely; to produce, as that which is untrue or
      not genuine; to fabricate; to counterfeit, as, a
      signature, or a signed document.
      [1913 Webster]

            That paltry story is untrue,
            And forged to cheat such gulls as you. --Hudibras.
      [1913 Webster]

            Forged certificates of his . . . moral character.
                                                  --Macaulay.

   Syn: To fabricate; counterfeit; feign; falsify.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

forged \forged\ (f[=o]rjd), adj.
   1. Not genuine; counterfeit; -- used mostly of signatures and
      documents. See forge, v. t., 4.

   Syn: bad.
        [WordNet 1.5 +PJC]

   2. shaped by strong pressure in a press, or by heatng and
      hammering; -- of metal objects.

   Note: Also used metaphorically of results requiring intense
         or difficult effort.
         [PJC]

WordNet (r) 3.0 (2006):

forged
    adj 1: reproduced fraudulently; "like a bad penny..."; "a forged
           twenty dollar bill" [syn: bad, forged]

Moby Thesaurus II by Grady Ward, 1.0:

73 Moby Thesaurus words for "forged":
   assembled, built, cast, concocted, constructed, cooked-up,
   counterfeit, crafted, created, custom, custom-built, custom-made,
   ersatz, extracted, fabricated, fabulous, fake, fancied, fantasied,
   fantastic, fashioned, fictional, fictitious, figmental, formed,
   gathered, grown, handcrafted, handmade, harvested, hatched, hokey,
   homemade, homespun, imitation, invented, legendary, machine-made,
   machined, made, made to order, made-up, man-made, manufactured,
   milled, mined, mock, molded, mythical, phony, plagiarized, prefab,
   prefabricated, processed, pseudo, put together, put-up, quasi,
   raised, ready-for-wear, ready-formed, ready-made, ready-prepared,
   ready-to-wear, refined, sham, shaped, smelted, synthetic,
   trumped-up, well-built, well-constructed, well-made