ὕπουλ-ος · hypoul-os — LSJ
extending inwards, under the surface of the flesh, enclosed, τὰ συριγγώδη καὶ ὅσα ὕ. ἐστι καὶ ἔντοσθε κεκοιλασμένα Hp. Medic. 11; ὅσα μὲν ἔχει στόμα μέγα καὶ οὐ ταχὺ συμφύεται, ταῦτα καίειν δεῖ, ὅπως ἡ ἐσχάρα ἐκεῖ πέσῃ· οὕτως γὰρ οὐκ ἔσται ὕπουλα, i.e. there will be no internal accumulation of pus, Arist. Pr. 863a12; also of the part affected, festering, purulent, σῶμα Cratin. 351, cf. Plu. Lyc. 4; ἐπιληψίαι Gal. Vict.Att. 1; σπλήν Pl. Ti. 72d.
metaph., with festering sores underneath, unsound, hollow, οἰδεῖ καὶ ὕ. ἐστιν [ἡ πόλις] Id. Grg. 518e; ὕ. τὴν ψυχὴν ποιήσει ib. 480b; ὕ. τέλμα treacherous, Plu. Rom. 18; ὕ. εὐνομία (v.l. αὐτονομία) hollow, unreal, Th. 8.64; ὕ. ἡσυχία D. 18.307; applied to the Trojan horse, S. Fr. 1105; κάλλος κακῶν ὕπουλον a fair outside, but fraught with ills below, Id. OT 1396; ὕ. μάντευμα false, fallacious, Paus. 3.7.3; φαντασίαι Gal. 7.203; λόγοι Babr. 44.4; of persons, false, deceitful, ἀνὴρ ὕ. δίκτυον κεκρ