pronoun
you (polite, archaic); your father (polite, archaic)
Archaic polite second-person pronoun, also used to refer to someone's father. In modern Japanese, あなた or お父様 are used instead.
古文書には「尊公のご意見を伺いたい」といった表現が見られる。
In old documents, expressions like 'I would like to hear your opinion, sir' can be found.
「尊公はご健在か」と尋ねるのは
Asking 'Is your father in good health?' using 尊公 is an old-fashioned way of showing respect to the listener's father.