σκληροκέφαλος
From LSJ
καὶ παρὰ δύναμιν τολμηταὶ καὶ παρὰ γνώμην κινδυνευταὶ καὶ ἐν τοῖς δεινοῖς εὐέλπιδες → they are bold beyond their strength, venturesome beyond their better judgment, and sanguine in the face of dangers
German (Pape)
[Seite 900] hartköpfig, Sp.
Greek (Liddell-Scott)
σκληροκέφᾰλος: -ον, ὁ ἔχων σκληρὰν κεφαλήν, ἰσχυρογνώμων, Θεοφάν. Νόνν.