[1] : The Collaborative International Dictionary of English v.0.48

faithless \faith"less\, a.
   1. not believing; not giving credit.
      1913 webster

            be not faithless, but believing.      --john xx. 27.
      1913 webster

   2. not believing on god or religion; specifically, not
      believing in the christian religion. --shak.
      1913 webster

   3. not observant of promises or covenants.
      1913 webster

   4. not true to allegiance, duty, or vows; perfidious;
      trecherous; disloyal; not of true fidelity; inconstant, as
      a husband or a wife.
      1913 webster

            a most unnatural and faithless service. --shak.
      1913 webster

   5. serving to disappoint or deceive; delusive; unsatisfying.
      "yonder faithless phantom." --goldsmith. --
      faith"lessly, adv.faith"lessness, n.
      1913 webster
see also:
faith"lessly faith"lessness 

[2] : WordNet (r) 2.0

faithless
     adj : deliberately and abominably disloyal or likely to betray
           trust or confidence; "the faithless benedict arnold";
           "a lying traitorous insurrectionist" syn: traitorous,
            unfaithful
see also:
traitorous unfaithful 

[3] : Moby Thesaurus II by Grady Ward, 1.0

81 moby thesaurus words for "faithless":
   machiavellian, agnostic, ambidextrous, apostate, artful, atheist,
   atheistic, capricious, changeable, changeful, collaborative,
   conscienceless, crafty, creedless, crooked, cunning, deceitful,
   derelict, disaffected, disbelieving, dishonest, disloyal, double,
   double-dealing, double-faced, double-minded, double-tongued,
   doublehearted, doubting, duplicitous, false, false-principled,
   falsehearted, fickle, fluctuating, freethinking, heathen,
   heretical, hypocritical, inconstant, incredulous, infidel,
   infidelic, insincere, irreligious, minimifidian, nonbelieving,
   not true to, nullifidian, of bad faith, pagan, perfidious,
   recreant, renegade, repudiative, sceptical, shifting, shifty,
   tergiversant, tergiversating, traitorous, treacherous, treasonable,
   treasonous, trothless, two-faced, unbelieving, unchristian,
   unconfident, unconverted, unconvinced, unfaithful, unloyal,
   unreliable, unscrupulous, unstable, unsteadfast, untrue,
   untrustworthy, wavering, without faith

Faithless >> F Words
Faithless, definition of term: Faithless
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