1. transitively,

a. to turn to: ἐπί τόν Θεόν, to the worship of the true God, Acts 26:20.

b. to cause to return, to bring back; figuratively, τινα ἐπί κύριον τόν Θεόν, to the love and obedience of God, Luke 1:16; ἐπί τέκνα, to love for the children, Luke 1:17; ἐν φρονήσει δικαίων, that they may be in (R. V. to walk in) the wisdom of the righteous, Luke 1:17; τινα ἐπί τινα, supply from the context ἐπί τήν ἀλήθειαν and ἐπί τήν ὁδόν, James 5:19f.

2. intransitive, (Winers Grammar, § 38, 1 (compare p. 26; Buttmann, 144 (126f)));

a. to turn, to turn oneself: ἐπί τόν κύριον and ἐπί τόν Θεόν, of Gentiles passing over to the religion of Christ, Acts 9:35; Acts 11:21; Acts 14:15; Acts 15:19; Acts 26:20, cf. 1 Peter 2:25; πρός τί, Acts 9:40; πρός τόν Θεόν, 1 Thessalonians 1:9; 2 Corinthians 3:16; ἀπό τίνος εἰς τί, Acts 26:18.

b. to turn oneself about, turn back: absolutely, Acts 16:18; followed by an infinitive expressing purpose, Revelation 1:12.

c. to return, turn back, come back; α. properly: Luke 2:20 Rec.; ; Acts 15:36; with the addition of ὀπίσω (as in Aelian v. h. 1, 6 (variant)), followed by an infinitive of purpose, Matthew 24:18: followed by εἰς with the accusative of place, Matthew 12:44; (Luke 2:39 T WH Tr marginal reading); εἰς τά ὀπίσω, Mark 13:16; Luke 17:31; ἐπί τί, to, 2 Peter 2:22. β. metaphorically: ἐπί τί, Galatians 4:9; ἐπί τινα, Luke 17:4 Rec., but G omits ἐπί σε; πρός τινα, ibid. L T Tr WH; ἐκ τῆς ἐντολῆς, to leave the commandment and turn back to a worse mental and moral condition, 2 Peter 2:21 R G; absolutely, to turn back morally, to reform: Matthew 13:15; Mark 4:12; Luke 22:32; Acts 3:19; Acts 28:27. In the middle and 2 aorist passive a. to turn oneself about, to turn around: absolutely, Matthew 9:22 R G; Mark 5:30; Mark 8:33; John 21:20.

b. to return: followed by πρός (WH text ἐπί) τινα, Matthew 10:13 (on which passage see εἰρήνη, 3 at the end); ἐπί τόν Θεόν, 1 Peter 2:25 (see 2 a. above); to return to a better mind, repent, John 12:40 (R G).