emperor

柯林斯詞典

1. N-COUNT/N-TITLE An emperor is a man who rules an empire or is the head of state in an empire. 皇帝
...the emperor of Japan. …日本天皇。

He'd dressed himself up as a Roman emperor for the fancy-dress party .
This type of porcelain was made specifically for the Chinese emperor and the imperial household .
Hirohito was Emperor of Japan from 1926 until his death in 1989.
The Pope granted Charlemagne the title of Holy Roman Emperor back in the 9th century .
Constantine was the first emperor to promote Christianity .