Lewis Short
tyrannĭcīda (noun M) : tyrannus-caedo
* A killer of a tyrant, a tyrannicide, Sen. Ira, 2, 23, 1; Plin. 7, 23, 23, § 87; Suet. Tib. 4; id. Vit. Luc.; Quint. 5, 10, 36; 5, 10, 59; 7, 3, 7; 7, 7, 2; 7, 7, 5; Tac. Or. 35.
Charlton T. Lewis, Charles Short, A Latin Dictionary