father-in-law
From LSJ
θεωρεῖται δὲ ἀνοησίᾳ κρείττονι νοήσεως → it is grasped only by means of an ignorance superior to intellection, it may be immediately cognised only by means of a non-intellection superior to intellection
P. and V. κηδεστής, ὁ, V. γαμβρός, ὁ, πενθερός, ὁ.