κατανοητέον
From LSJ
Ἐάν γάρ ἀποδιδῷ τις τί ἐστιν αὐτῶν ἑκατέρῳ τό ζῴῳ εἶναι, ἴδιον ἑκατέρου λόγον ἀποδώσει (Aristotle, Categoriae 1a) → For if anyone gives an explanation of what it is for each of them to be an animal, he will give the same explanation of each
English (LSJ)
A one must observe, learn, Pl.Plt.305c, Porph.Marc.27; one must consider, πάλιν περί τινος Ph.1.83.
Greek (Liddell-Scott)
κατανοητέον: ῥημ. ἐπίθ., πρέπει νὰ μάθῃ τις, νὰ παρατηρήσῃ, Πλάτ. Πολιτ. 305C.
Dutch (Woordenboekgrieks.nl)
κατανοητέον, adj. verb. van κατανοέω, men moet beseffen.