G0569
ἀπιστέω
to disbelieve
ἀπιστέω, -ῶ (ἄπιστος), [in LXX: Wis.1:2 10:7 12:17 18:13, Sir.1:27, 2Ma.8:13 * ;] __1. to disbelieve, be faithless: Mrk.16:11, 16, Luk.24:11, 41, Act.28:24, 1Pe.2:7; so prob. also Rom.3:3, 2Ti.2:13 (ICC, CGT, in ll; MM, see word). __2. = ἀπειθέω (Hdt.; on this sense in Ro, 2Ti, ll. with, see Vaughan on Ro, l.with; Lft., Notes, 265; Thayer, see word).† (AS)
Full Thayer's lexicon entry
ἀπιστέω — apistéō
ἀπιστέω, ἀπίστω; (imperfect ἠπίστουν); 1 aorist ἠπίστησα; (ἄπιστος);
1. to betray a trust, be unfaithful: 2Ti 2:13 (opposed to πιστός μένει); Rom 3:3; (others deny this sense in the N. T.; cf. Morison or Meyer on Romans, the passage cited; Ellicott on 2 Timothy, the passage cited).
2. to have no belief, disbelieve: in the news of Christ's resurrection, Mar 16:11; Luk 24:41; with dative of person, Luk 24:11; in the tidings concerning Jesus the Messiah, Mar 16:16 (opposed to πιστεύω) (so 1Pe 2:7 T Tr WH); Act 28:24. (In Greek writings from Homer down.)
8 occurrences
Mark (2), Luke (2), Acts (1), Romans (1), II Timothy (1), I Peter (1)