οὐκ ἔφη: he said no. Certain verbs, beyond a mere negation, have their meaning at times precisely reversed by οὐ: i.e. οὔ φημι, nego, deny; οὐχ ὑπισχνοῦμαι, refuse; οὐκ ἀξιῶ, regard as unworthy; οὐκ ἐῶ, veto, forbid.
πρᾶγμά τι ἢ κτἑ.: the Platonic Socrates often begins his examinations thus. Cf. 330 d, 332 a, 358 d.