ἀρρανής
From LSJ
Περὶ τοῦ ἐπέκεινα τοῦ νοῦ κατὰ μὲν νόησιν πολλὰ λέγεται, θεωρεῖται δὲ ἀνοησίᾳ κρείττονι νοήσεως → On the subject of that which is beyond intellect, many statements are made on the basis of intellection, but it may be immediately cognised only by means of a non-intellection superior to intellection
Spanish (DGE)
-ές
quizá f.l. por ἀρραγής irrompible, inquebrantable πέτραν ... τὴν ἀρρανῆ ... τοῦ Σωτῆρος δύναμιν ὀνομάζει Cyr.Al.M.70.701B.