How does a monk address parents and relatives? In Theravada tradition, after one becomes a monk. Does he still call his parents and relatives the same as before he ordains. Or does he call them like everybody else? Does he call his parents "mom" and "dad", his siblings "brother" and "sister",...?
It may depend on the tradition, but in the Pali suttas, the language changes unequivocally to more formal modes of address like &quot;gahapati&quot; (householder), &quot;upaasaka/upaasikaa&quot; (lay follower), etc.

Then the clansman Raṭṭhapāla rose from his seat, and after paying homage to the Blessed One, he departed, keeping him on his right. He went to his parents and told them: “Mother and father, as I understand the Dhamma taught by the Blessed One, it is not easy while living in a home to lead the holy life, utterly perfect and pure as a polished shell. I wish to shave off my hair and beard, put on the yellow robe, and go forth from the home life into homelessness. Give me permission to go forth from the home life into homelessness.”

...

Then the venerable Raṭṭhapāla’s former wives clasped his feet and said to him: “What are they like, my lord’s son, the nymphs for whose sake you lead the holy life?”
“We do not lead the holy life for the sake of nymphs, sisters.”
“Our lord’s son Raṭṭhapāla calls us ‘sisters,’” they cried and right there they fainted.
Then the venerable Raṭṭhapāla told his father: “Householder, if there is a meal to be given, then give it. Do not harass us.”

-- (MN 82 - Bodhi, trans)