ἀναμαρτής
From LSJ
θεωρεῖται δὲ ἀνοησίᾳ κρείττονι νοήσεως → it is grasped only by means of an ignorance superior to intellection, it may be immediately cognised only by means of a non-intellection superior to intellection
English (LSJ)
ές, unerring, Hsch. s.v. νημερτής.
Spanish (DGE)
-ές infalible, que no falla Hsch.s.u. νημερτής.