son of a prince, king, queen, emperor or empress, or other high-ranking person (such as a grand duke)
A prince is a male member of a royal family. A female member is called a princess.
Each royal family has its own rules saying who is called a prince. In most of these families, the son of a king or a queen is a prince. In some families, the son of a prince is also a prince. In Monaco and Lichtenstein, the ruler of the country is called the prince.