1) unfaithful, faithless, (not to be trusted, perfidious)
2a) of things
3) unbelieving, incredulous
3a) without trust (in God)
Part of Speech: adjective
Citing in TDNT: 6:174, 849
From G1 (as a negative particle) and G4103; (actively) disbelieving, that is, without Christian faith (specifically a heathen); (passively) untrustworthy (person), or incredible (thing): - that believeth not, faithless, incredible thing, infidel, unbeliever (-ing).
|b lack in trust||31.98|
These two sites give similar information, with the definition from several dictionaries and statistics on the use of the word.
Perseus Digital Library
University of Chicago's Logion lexicon
Thayer's dictionary plus other information.
From this site's dictionary (in Italian)
Click on the first column to search for that word as a form of the root ἄπιστος; click on the second column to search for that grammatical form of the root ἄπιστος; click on the third column to search for that word and grammatical form; click on the total to search for the root ἄπιστος.