Source : Webster's Revised Unabridged Dictionary (1913)

Mortiferous \Mor"tif"er*ous\, a. [L. mortifier; mors, mortis,
   death + ferre to bring: cf. F. mortif[`e]re.]
   Bringing or producing death; deadly; destructive; as, a
   mortiferous herb. --Gov. of Tongue.