Lexicon :: Strong's G228 - alēthinos

ἀληθινός, -ή, -όν, (frequent in secular writings from Plato down; [twenty-three times in John's writings; only five (according to Lachmann six) times in the rest of the N. T.]);
1. "that which has not only the name and semblance, but the real nature corresponding to the name" (Tittmann, p. 155; ["particularly applied to express that which is all that it pretends to be, for instance, pure gold as opposed to adulterated metal" Donaldson, New Crat. § 258; see, at length, Trench, § viii.]), in every respect corresponding to the idea signified by the name, real and true, genuine;
a. opposed to what is fictitious, counterfeit, imaginary, simulated, pretended: θεός (אֱמֶת אֱלֹהַי, 2 Chronicles 15:3), 1 Thessalonians 1:9; Hebrews 9:14 Lachmann; John 17:3; 1 John 5:20. (ἀληθινοὶ φίλοι, Demosthenes, Philippians 3, p. 113, 27.)
b. it contrasts realities with their semblances: σκηνή, Hebrews 8:2; the sanctuary, Hebrews 9:24. (ὁ ἵππος contrasted with ὁ ἐν τῇ εἰκόνι, Aelian v. h. 2, 3.)
c. opposed to what is imperfect, defective, frail, uncertain: John 4:23, 37; John 7:28; used without adjunct of Jesus as the true Messiah, Revelation 3:7; φῶς, John 1:9; 1 John 2:8; κρίσις, John 8:16 (L T Tr WH; Isaiah 59:4); κρίσεις, Revelation 16:7; Revelation 19:2; ἄρτος, as nourishing the soul unto life everlasting, John 6:32; ἄμπελος, John 15:1; μαρτυρία John 19:35; μάρτυς, Revelation 3:14; δεσπότης, Revelation 6:10; ὁδοί, Revelation 15:3; coupled with πιστός, Revelation 3:14; Revelation 19:11; substantively, τὸ ἀληθινόν the genuine, real good, opposed to external riches, Luke 16:11 ([οἷς μέν γὰρ ἀληθινὸς πλοῦτος ἐν οὐρανῷ, Philo de praem, et poen. § 17, p. 425, Mang. edition; cf. Wetstein on Luke, the passage cited]; ἀθληταί, Polybius 1, 6, 6).
2. equivalent to ἀληθής, true, veracious, sincere, (often so in the Sept.): καρδία, Hebrews 10:22 (μετ’ ἀληθείας ’ν καρδίᾳ ἀληθινῇ, Isaiah 38:3); λόγοι, Rev. (Rev 19:9); Rev 21:5; 22:6 (Plutarch, apoph, p. 184 e.). [Cf. Cremer, 4te Aufl. under the word ἀλήθεια.]

BLB Scripture Index of Thayer's