Lewis Short
occīsĭo (noun F) : 1. occīdo
* A massacre, slaughter, murder (class. but rare, except in eccl. Lat.; sometimes interchanged in the MSS. with occidio): si caedes et occisio facta non erit,Cic. Caecin. 14, 41: parentis,id. Inv. 1, 26, 37; App. M. 6, p. 184; Aur. Vict. Vir. Ill. 14: aestimati sumus sicut oves occisionis,Vulg. Psa. 43, 21: gladium ad occisionem,id. Jer. 15, 3.
Charlton T. Lewis, Charles Short, A Latin Dictionary