UBS Dictionary of the Greek New Testament

Sense 1: unbelievable, impossible to be believed

Semantic entry: 31.40

Semantic domains: Hold a View, Believe, Trust

Subdomains: Believe To Be True

Definition: (derivative of ἀπιστέω[a] ‘to not believe,’ 31.39: ἀπιστέω) pertaining to not being believable

Sense 2: to be unbelieving, to be lacking in trust

Semantic entry: 31.98

Semantic domains: Hold a View, Believe, Trust

Subdomains: Trust, Rely

Definition: (derivative of ἀπιστέω [source selector 000001][b] ‘to not believe (in),’ 31.97: ἀπιστέω / 31.97: ἀπιστία) pertaining to not believing, with the implication of refusing to believe

Sense 1: one who is not a believer, unbeliever

Semantic entry: 31.106

Semantic domains: Hold a View, Believe, Trust

Subdomains: Be a Believer, Christian Faith

Definition: one who does not believe the good news about Jesus Christ

Notes: It is clearly not enough in most languages to render ἄπιστος [source selector 000001][b] in RV MRK 9:19 · LV MRK 9:19 · Read together MRK 9:19 (see 31.98: ἄπιστος).

Sense 2: non-Christian

Semantic entry: 11.19

Semantic domains: Groups and Classes of Persons and Members of Such Groups and Classes

Subdomains: Socio-Religious

Definition: a person who does not belong to the group of believers in Christ{N:001}

Notes: In RV CO1 7:15 · LV CO1 7:15 · Read together CO1 7:15 it may be necessary to indicate the so-called goal of belief or trust, for example, ‘if one who is not a believer in Christ’ or ‘if the one who is not a follower of Christ.’