Lewis Short
magmentum (noun N) : contr. from magimentum, from root mag; cf. mactare and mactus.—In relig. lang.
* That which magnifies or glorifies, an offering, sacrifice, Inscr. Orell. 2489; 2490; Inscr. Grut. 23, 12; 229, 1; Arn. 7, 24; cf. in preced.,Varr. L. L. 5, § 112 Müll.
Charlton T. Lewis, Charles Short, A Latin Dictionary