ἐλευθέριον
From LSJ
ἵνα οὖν μηδ' ἐν τούτῳ δῷ αὐτοῖς λαβήν (Photius, Fragments on the Epistle to the Romans 483.26) → so that he doesn't give them even here a handle (= an opportunity for refutation)
Russian (Dvoretsky)
ἐλευθέριον: τό Arst., Xen. = ἐλευθεριότης.