Definition
(actively) disbelieving, i.e. without Christian faith (specially, a heathen); (passively) untrustworthy (person), or incredible (thing)
Derivation
from G1 (Α) (as a negative particle) and G4103 (πιστός);
King James Version Usage
that believeth not, faithless, incredible thing, infidel, unbeliever(-ing)