1) (of) a chemical substance able to prevent disease, especially by destroying germs (antiseptic)
2) not able to produce offspring, fruit etc; without a productive purpose; producing nothing; free from living germs (sterile)
(kinds of) very small living things, many of which cause disease or help dead animals and plants to decay
microorganisms
the process of infecting or being infected, especially the communication of disease through the air or water; an infectious disease
contamination
