ἀναπότρεπτος

From LSJ

ἢ λέγε τι σιγῆς κρεῖττον ἢ σιγὴν ἔχε → either say something better than silence or keep silence (Menander)

Source

Spanish (DGE)

-ον
firme, irrevocable γνώμη PMasp.98.4 (VI d.C.)
como glos. a ἀλίαστος Sch.Er.Il.2.797 (p.170).