Webster's Revised Unabridged Dictionary
L. mortifier,; mors, mortis, death + ferre, to bring: cf. F. mortifère,
Chambers's Twentieth Century Dictionary
L. mors, death, ferre, to bring.
The latter, if burned to ashes in the fire, possesses mortiferous influence over enemies.
"Journals Of Expeditions Of Discovery Into Central Australia And Overland" by Edward John Eyre
But whatever it is in any other Country, 'tis certainly Mortiferous in ours.
"Acetaria: A Discourse of Sallets" by John Evelyn