infective

from WordNet (r) 3.0 (2006)

infective
    adj 1: able to cause disease; "infective agents"; "pathogenic
           bacteria" [syn: {infective}, {morbific}, {pathogenic}]
    2: caused by infection or capable of causing infection; "viruses
       and other infective agents"; "a carrier remains infective
       without himself showing signs of the disease" [syn:
       {infectious}, {infective}]

from The Collaborative International Dictionary of English v.0.48

Infective \In*fect"ive\, a. [L. infectivus pertaining to
   dyeing.]
   Infectious. --Beau. & Fl.
   [1913 Webster]

         True love . . . hath an infective power. --Sir P.
                                                  Sidney.
   [1913 Webster]