Source : Webster's Revised Unabridged Dictionary (1913)

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

         True love . . . hath an infective power. --Sir P.
                                                  Sidney.

Source : WordNet®

infective
     adj 1: able to cause disease; "infective agents"; "pathogenic
            bacteria" [syn: {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}]