• 陛下へいか — His/Her Majesty
• 天皇陛下てんのうへいか — His Majesty the Emperor
• 皇后陛下こうごうへいか — Her Majesty the Empress

The left radical ⻖ (こざとへん) often relates to land or structures. 陛 originally referred to stairways in palaces — symbolizing a rise to meet authority. Today, it’s almost exclusively seen in honorifics for royalty, especially in the phrase 陛下.