The Collaborative International Dictionary of English v.0.48:

Untrue \Un*true\, adv.
   Untruly. [Obs. or Poetic] --Chaucer.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Untrue \Un*true"\, a.
   1. Not true; false; contrary to the fact; as, the story is
      untrue.
      [1913 Webster]

   2. Not faithful; inconstant; false; disloyal. --Chaucer.
      [1913 Webster]

WordNet (r) 3.0 (2006):

untrue
    adj 1: not according with the facts; "unfortunately the
           statement was simply untrue"
    2: not true to an obligation or trust; "is untrue to his highest
       opportunity and duty"-Bruno Laske
    3: not accurately fitted; not level; "the frame was out of
       true"; "off-level floors and untrue doors and windows" [syn:
       out of true, untrue]
    4: (used especially of persons) not dependable in devotion or
       affection; unfaithful; "a false friend"; "when lovers prove
       untrue" [syn: false, untrue]

Moby Thesaurus II by Grady Ward, 1.0:

103 Moby Thesaurus words for "untrue":
   aberrant, abroad, adrift, all abroad, all off, all wrong, amiss,
   askew, astray, at fault, awry, beside the mark, capricious,
   contrary to fact, corrupt, deceitful, deceptive, defective,
   delusive, derelict, deviant, deviational, deviative, devious,
   disaffected, dishonest, dishonorable, disloyal, disregardful,
   distorted, duplicitous, errant, erring, erroneous, faithless,
   fallacious, false, faultful, faulty, fickle, flawed, forsworn,
   heretical, heterodox, hypocritical, illogical, illusory, imperfect,
   imprecise, in error, inaccurate, inattentive, inconstant,
   incorrect, inexact, inobservant, insincere, misleading, mistaken,
   negligent, nonadherent, noncompliant, nonconforming, nonobservant,
   not right, not true, not true to, of bad faith, off, off the track,
   out, peccant, perfidious, perjured, perverse, perverted, recreant,
   self-contradictory, specious, straying, substandard, traitorous,
   treacherous, trothless, truthless, two-faced, uncompliant,
   unconforming, undependable, unfactual, unfaithful, unfounded,
   unloyal, unobservant, unorthodox, unprecise, unproved, unreliable,
   unsound, unsteadfast, untrustworthy, wide, wrong