Adjective has 2 senses

• infective(s = adj.all) morbific, pathogenic - able to cause disease; "infective agents"; "pathogenic bacteria"

Derived form verb infect₁, verb infect₂

• infective(s = adj.all) infectious - caused by infection or capable of causing infection; "a carrier remains infective without himself showing signs of the disease"; "viruses and other infective agents"

Derived form verb infect₁, verb infect₂