Duke (noun)

1. A nobleman of high rank in feudal Europe, especially a member of the highest grade of the peerage in the UK and in certain other countries.
2. A male ruler of a duchy.
3. A person of high rank or status, especially in a particular field.

Origin:

Middle english: from old french duc, of germanic origin; related to dutch hertog and german herzog.

Examples:

1. The Duke of Wellington was one of England's greatest military leaders.
2. He was a duke in the kingdom of Spain.
3. She is considered a duke in the field of technology.
4. The Duke of Windsor was a beloved figure.
5. The Duke of Edinburgh was a prince consort.