Word: apistoj

Pronounce: ap'-is-tos

Strongs Number: G571

Orig: from 1 (as a negative particle) and 4103; (actively) disbelieving, i.e. without Christian faith (specially, a heathen); (passively) untrustworthy (person), or incredible (thing):--that believeth not, faithless, incredible thing, infidel, unbeliever(-ing). G1

Use: TDNT-6:174,849 Adjective

Heb Strong:

1) unfaithful, faithless, (not to be trusted, perfidious)
2) incredible
2a) of things
3) unbelieving, incredulous
3a) without trust (in God)