faithless

from WordNet (r) 3.0 (2006)

faithless
    adj 1: having the character of, or characteristic of, a traitor;
           "the faithless Benedict Arnold"; "a lying traitorous
           insurrectionist" [syn: {faithless}, {traitorous},
           {unfaithful}, {treasonable}, {treasonous}]

from The Collaborative International Dictionary of English v.0.48

Faithless \Faith"less\, a.
   1. Not believing; not giving credit.
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            Be not faithless, but believing.      --John xx. 27.
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   2. Not believing on God or religion; specifically, not
      believing in the Christian religion. --Shak.
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   3. Not observant of promises or covenants.
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   4. Not true to allegiance, duty, or vows; perfidious;
      trecherous; disloyal; not of true fidelity; inconstant, as
      a husband or a wife.
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            A most unnatural and faithless service. --Shak.
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   5. Serving to disappoint or deceive; delusive; unsatisfying.
      "Yonder faithless phantom." --Goldsmith. --
      {Faith"less*ly}, adv.{Faith"less*ness}, n.
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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