The Collaborative International Dictionary of English v.0.48:

Inaccurate \In*ac"cu*rate\, a.
   Not accurate; not according to truth; inexact; not quite
   correct; incorrect; erroneous; as, in inaccurate man,
   narration, copy, judgment, calculation, etc.

   Note: The term inaccurate is usually used when an assertion
         or result is near to the truth, but not exactly, or has
         some basis for belief; however, it is sometimes used as
         a gentle euphemism for wrong even if the error is
         flagrant.
         [1913 Webster +PJC]

               The expression is plainly inaccurate. --Bp. Hurd.

   Syn: Inexact; incorrect; erroneous; faulty; imperfect;
        incomplete; defective.
        [1913 Webster]

WordNet (r) 3.0 (2006):

inaccurate
    adj 1: not exact; "an inaccurate translation"; "the thermometer
           is inaccurate" [ant: accurate]

Moby Thesaurus II by Grady Ward, 1.0:

113 Moby Thesaurus words for "inaccurate":
   adulterated, aleatoric, aleatory, all wet, amiss, amorphous,
   approximate, approximative, awry, blemished, blobby, blurred,
   blurry, broad, chance, chancy, chaotic, cold, confused, damaged,
   defective, deficient, disordered, erroneous, fallacious, fallible,
   false, faulty, flawed, foggy, found wanting, fuzzy, general, hazy,
   hit-or-miss, ill-defined, illogical, immature, impaired, imperfect,
   imprecise, impure, inadequate, inchoate, incoherent, incomplete,
   incorrect, indecisive, indefinable, indefinite, indeterminable,
   indeterminate, indistinct, inexact, lacking, lax, loose, makeshift,
   mediocre, mistaken, mixed, negligent, nonspecific, not perfect,
   obscure, off, orderless, out of line, out of plumb, out of square,
   out of true, partial, patchy, random, shadowed forth, shadowy,
   shapeless, short, sketchy, specious, stochastic, sweeping, unclear,
   unconscientious, uncritical, undefined, undestined, undetermined,
   undeveloped, uneven, unexacting, unfactual, unfinical, unfinished,
   unfussy, unmeticulous, unpainstaking, unparticular, unperfected,
   unplain, unprecise, unpunctilious, unpunctual, unrigorous,
   unscrupulous, unsound, unspecified, unthorough, untrue, vague,
   veiled, wanting, wrong