ἀμετάπτωτος
From LSJ
τὸ γὰρ πράττειν τοῦ λέγειν καὶ χειροτονεῖν ὕστερον ὂν τῇ τάξει, πρότερον τῇ δυνάμει καὶ κρεῖττόν ἐστιν (Demosthenes 3.15) → for action, even though posterior in the order of events to speaking and voting, is prior in importance and superior
English (LSJ)
ον,
A unchanging, unchangeable, λόγοι μόνιμοι καὶ ἀ. Pl.Ti.29b; ἐπιστήμη Arist.Top.139b33; ἡ ἀρετή Id.MM 1209b13, Stoic.1.50, etc.; κατάληψις ἀ. ὑπὸ λόγου Zenoib.1.20; πίστεις Phld.Rh.1.378S. (Sup.). b not losing its power, of medicine, Gal.12.422. II of persons, Plu.2.659f. Adv. -τως Id.Dio 14, cf. Phld.Rh.1.158S., Polystr.p.29W.