Your Majesty
His Majesty, Her Majesty
noun, suffix
Your highness I am so below you because your majesty is so great and amazing!
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
陛下、恐れ入りますが会議にご出席のご予定だったのでは。
Your Majesty, I’m sorry to impose but you were supposed to attend the meeting.