contermino
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
Latin > English (Lewis & Short)
contermĭno: āre, v. n. conterminus: alicui,
I to be a borderer, to border upon; perh. only Amm. 14, 2, 5; 23, 6, 45.
Latin > French (Gaffiot 2016)
contermĭnō, āre (conterminus), intr., être voisin, avoisiner [alicui ] : Amm. 14, 2, 5 ; 23, 6, 45.