germ-theory
Germ theory. 1. (Biol.) Defn: The theory that living organisms can be produced only by the development of living germs. Cf. Biogenesis, Abiogenesis. 2. (Med.) The theory which attributes contagious and infectious diseases, suppurative lesions, etc., to the agency of germs. The science of bacteriology was developed after this theory had been established.