resistless
From LSJ
ἄλογον δὴ τὸ μήτε μάχης ἄρξασθαι μήτε τοὺς φίλους φυλάξαι, ἐὰν ὑπό γε τῶν βαρβάρων ἀδικῆσθε → It is irrational neither to begin battle nor to guard the friends, if you are ever wronged by the foreigners
English > Greek (Woodhouse)
adjective
P. and V. δύσμαχος (Plato), ἀνίκητος (Plato), Ar. and P. ἄμαχος (Plato), P. δυσπολέμητος, δυσπάλαιστος, ἀπρόσμαχος, ἀδηριτος.
not to be avoided: P. and V. ἄφυκτος.
impossible to deal with: P. and V. ἄπορος, ἀμήχανος (rare P.).