- the sovereign ruler of a grand duchy, ranking just below a king
- in czarist Russia, a prince of the royal family
grand dukegrand duke
- A nobleman who is the sovereign of a grand duchy.
- A son or grandson of a czar in the male line.
- Used as the title for such a nobleman.
(plural grand dukes)
- Ruler or monarch of a grand duchy.
- Son or grandson of a czar (emperor) of the Russian Empire. (A more literal translation of the Russian would be "grand prince".)