regicide
noun /ˈredʒɪsaɪd/
/ˈredʒɪsaɪd/
[uncountable, countable] (formal)- the crime of killing a king or queen; a person who is guilty of this crimeTopics Crime and punishmentc2Word Originmid 16th cent.: from Latin rex, reg- ‘king’ + -cide, probably suggested by French régicide.