Which is the appropriate word among the following for the given sentence.
Murder of a king or a queen.

Regicide

The appropriate word among the following for the given sentence is regicide.

• Sojourn means a temporary stay in a place.
• Synod is a meeting of church leaders.
• Zodiac is a belt of stars that circles the sky.
• Regicide is the murder of a king or queen.

The word regicide is the best fit because it conveys the idea of the specific act of killing a king or queen. The word comes from the Latin words "rex," meaning "king," and "caedere," meaning "to kill."