duke      
noun [ C ] uk/dʒuːk/ us/duːk/
 公爵;小公国的君主
a man of very high rank in a country, or the ruler of a small independent country
 - More examples
 - They claim to be descendants of a French duke.
 - They trace their line of descent back to a French duke.
 - The duke is desirous of meeting you.
 - The order of precedence for titled nobility in Britain is duke, marquis, earl, viscount, baron.
 - The play revolves round the betrothal of a duke to a doctor's daughter.