γνωριστέον
From LSJ
αὐτὸν κέκρουκας τὸν βατῆρα τοῦ λόγου → you have struck the very threshold of the argument, you have struck the most important and chiefmost point
English (LSJ)
A one must know, Arist.EN1180b22; one may recognize, Alex.Trall.1.15.
Greek (Liddell-Scott)
γνωριστέον: ῥημ. ἐπίθ., πρέπει τις νὰ γνωρίσῃ, Ἀριστ. Ἠθ. Ν. 10. 9,16.
French (Bailly abrégé)
adj. verb. de γνωρίζω.