Fāith'less, a.
a. 1. Not believing; not giving credit.
Sense 2. Not believing in God or religion; specifically, not believing in the Christian religion. “A faithless Jew.” Shak.
Sense 3. Not observant of promises.
Sense 4. Not true to allegiance, duty, or vows; as, a faithless subject, servant, or wife. “A most unnatural and faithless service.” Shak.
Sense 5. Serving to disappoint or deceive; deluding; delusive; unsatisfying. “Yonder faithless phantom.” Goldsmith.