Final answer:
The root of the word 'regicide' is 'reg', which means 'to rule'. In the word 'regicide', 'cide' means 'kill' or 'killer', so 'regicide' means the act of killing a king or ruler.
Step-by-step explanation:
The root of the word 'regicide' is a: reg which means 'to rule'. This root comes from the Latin word 'rex', meaning 'king' or 'ruler'.
Therefore, the meaning of the root 'reg' is 'to rule'. In the word 'regicide', 'cide' means 'kill' or 'killer', so 'regicide' means the act of killing a king or ruler.
For example, in history, the act of regicide was committed by individuals who assassinated rulers or leaders.