The Collaborative International Dictionary of English v.0.48:

Morbific \Mor*bif"ic\, Morbifical \Mor*bif"ic*al\, a. [L. morbus
   disease + -ficare (in comp.) to make: cf. F. morbifique. See
   -fy.]
   Causing disease; generating a sickly state; as, a morbific
   matter.
   [1913 Webster]