John 8:55 καὶ οὐκ ἐγνώκατε αὐτόν, ἐγὼ δὲ οἶδα αὐτόν κἂν εἴπω ὅτι οὐκ οἶδα αὐτόν, ἔσομαι ὅμοιος ὑμῖν ψεύστης· ἀλλὰ οἶδα αὐτὸν καὶ τὸν λόγον αὐτοῦ τηρῶ.
You have not known him, but I know him. If I said, 'I don't know him,' I would be like you, a liar. But I know him, and keep his word.
Noun: Nominative Singular Masculine

Romans 3:4 μὴ γένοιτο γινέσθω δὲ ὁ θεὸς ἀληθής, πᾶς δὲ ἄνθρωπος ψεύστης καθάπερ / καθὼς γέγραπται· ὅπως ἂν δικαιωθῇς ἐν τοῖς λόγοις σου καὶ νικήσεις ἐν τῷ κρίνεσθαί σε.
May it never be! Yes, let God be found true, but every man a liar. As it is written, "That you might be justified in your words, and might prevail when you come into judgment."
Noun: Nominative Singular Masculine

1 John 2:4 ὁ λέγων ὅτι ἔγνωκα αὐτόν καὶ τὰς ἐντολὰς αὐτοῦ μὴ τηρῶν, ψεύστης ἐστίν καὶ ἐν τούτῳ ἡ ἀλήθεια οὐκ ἔστιν·
One who says, "I know him," and doesn't keep his commandments, is a liar, and the truth isn't in him.
Noun: Nominative Singular Masculine

1 John 2:22 τίς ἐστιν ὁ ψεύστης εἰ μὴ ὁ ἀρνούμενος ὅτι Ἰησοῦς οὐκ ἔστιν ὁ Χριστός; οὗτός ἐστιν ὁ ἀντίχριστος ὁ ἀρνούμενος τὸν πατέρα καὶ τὸν υἱόν.
Who is the liar but he who denies that Jesus is the Christ? This is the Antichrist, he who denies the Father and the Son.
Noun: Nominative Singular Masculine

1 John 4:20 ἐάν τις εἴπῃ ὅτι ἀγαπῶ τὸν θεόν καὶ τὸν ἀδελφὸν αὐτοῦ μισῇ, ψεύστης ἐστίν· ὁ γὰρ μὴ ἀγαπῶν τὸν ἀδελφὸν αὐτοῦ ὃν ἑώρακεν, τὸν θεὸν ὃν οὐχ ἑώρακεν οὐ δύναται ἀγαπᾶν.
If a man says, "I love God," and hates his brother, he is a liar; for he who doesn't love his brother whom he has seen, how can he love God whom he has not seen?
Noun: Nominative Singular Masculine