καρδιοφύλαξ
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
English (LSJ)
[ῠ], ᾰκος, ὁ,
A breastplate, Plb.6.23.14.
German (Pape)
[Seite 1327] ακος, ὁ, Brustschild, der das Herz bewacht, Pol. 6, 23, 14.