a male member of a royal family other than the sovereign (especially the son of a sovereign)
"After years in exile, Prince William finally returned to Buckingham Palace as the heir apparent."
A (male) ruler, a sovereign; a king, monarch.
"After years of waiting for his father to pass away, the prince finally ascended to the throne as the new ruler of the kingdom."
In plain English: A prince is a male member of a royal family who rules over a country or holds a high rank within it.
"The prince waved to the crowd from his balcony during the royal parade."
Usage: Use "prince" to refer specifically to a male member of a royal family who holds a title below that of king or queen, such as the son of a reigning monarch. Do not use it to mean a generic leader or ruler unless the person actually holds a hereditary royal title in a monarchy.
The title of a prince
"After his grandfather passed away, the young boy officially received the title of prince at the coronation ceremony."
The word prince comes from the Latin phrase prīnceps, meaning "first head," which was formed by combining words for "first" and "seize." It entered English through Anglo-Norman after displacing native terms like atheling and drighten.