Сэр (Sir, sire) - a respectful form of address for someone of high social status, especially a king.
We honestly did not know we had trespassed on your lands, sire .
The word “sir,” which is a respectful term used to address a man, derives from the word “sire.” When written with a capital “S,” it is used as the distinctive title of a knight or baronet. The word “sire” is now considered archaic. But it was once used to refer to an authority or a person of general importance.