Oxymōron (ὀξύμωρον pointedly or cleverly foolish) is the juxtaposition of words apparently contradictory of each other.
νόμος ἄνομος
a law that is no law Ag. 1142, ἄχαρις χάρις
a graceless grace Pr. 545, πίστις ἀπιστοτάτη
most faithless faith 1.67, αὐτοὶ φεύγοντας φεύγουσι
they themselves are flying from those who fly 7.70.