adj not believing; not giving credit.
2. faithless ·adj not observant of promises or covenants.
3. faithless ·adj serving to disappoint or deceive; delusive; unsatisfying.
4. faithless ·adj not believing on god or religion; specifically, not believing in the christian religion.
5. faithless ·adj not true to allegiance, duty, or vows; perfidious; trecherous; disloyal; not of true fidelity; inconstant, as a husband or a wife.