Etymology 2
Learned borrowing from Medieval Latin rēgicida (“king-killer”).
Noun
regicide (plural regicides)
- One who kills a king. [from 1540s]
- Synonyms: regicider, kingslayer
- Hyponym: tyrannicide
- Coordinate term: reginacide
2014 September 15, Martin Gayford, “There's more to Ming than a vase [print version: 16 August 2014, pp. R6–R7]”, in The Daily Telegraph (Review):The fact that the Yongle emperor was therefore a usurper, regicide and nepoticide (nephew-killer) made compiling the Veritable Record – or official history – of his reign a most dangerous scholarly post. The official given this ticklish task managed to survive several drafts, finally producing one that pleased his master as it omitted the dead nephew's reign altogether.