The Collaborative International Dictionary of English v.0.48:

Modify \Mod"i*fy\, v. t. [imp. & p. p. Modified; p. pr. & vb.
   n. Modifying.] [F. modifier, L. modificare, modificari;
   modus limit + -ficare (in comp.) to make. See Mode, and
   -fy.]
   1. To change somewhat the form or qualities of; to change a
      part of something while leaving most parts unchanged; to
      alter somewhat; as, to modify a contrivance adapted to
      some mechanical purpose; to modify the terms of a
      contract.
      [1913 Webster]

   2. To limit or reduce in extent or degree; to moderate; to
      qualify; to lower.
      [1913 Webster]

            Of his grace
            He modifies his first severe decree.  --Dryden.
      [1913 Webster]

WordNet (r) 3.0 (2006):

modified
    adj 1: changed in form or character; "their modified stand made
           the issue more acceptable"; "the performance of the
           modified aircraft was much improved" [ant: unmodified]
    2: mediocre [syn: limited, modified]

Moby Thesaurus II by Grady Ward, 1.0:

36 Moby Thesaurus words for "modified":
   altered, better, changeable, changed, conditioned, converted,
   degenerate, deviant, divergent, hedged, hedged about, improved,
   leavened, limited, metamorphosed, metastasized, mitigated,
   modulated, mutant, qualified, rebuilt, reformed, renewed, reserved,
   restricted, revived, revolutionary, seasoned, softened, subversive,
   tempered, transformed, translated, transmuted, unmitigated,
   worse