Greek word
ápistos
ἄπιστος
What it means
disbelieving, i.e. without Christian faith
(actively) disbelieving, i.e. without Christian faith (specially, a heathen); (passively) untrustworthy (person), or incredible (thing)
Where it comes from
from A (Α) (as a negative particle) and pistós (πιστός)