A more thorough explanation:

Definition: Regicide is the act of killing or murdering a king. It can also refer to a person who kills a king, especially if they are under the king's rule.

Examples:

• When Julius Caesar was assassinated, it was considered a regicide because he was the ruler of Rome at the time.
• In 1649, King Charles I of England was executed by beheading, which was a regicide.
• Some people believe that the death of King Tutankhamun was a regicide, although there is no concrete evidence to support this theory.

These examples illustrate how regicide refers to the killing of a king, whether it is through assassination, execution, or other means. It is a serious crime that is often associated with political upheaval and instability.