Host - An organism that harbors a parasite or another organism where there is a symbiotic relationship between the two organisms. In some cases, the relationship is commensal, or mutually beneficial, but in the case of a parasite and host, the host may be hurt by the parasite's presence.⏎
Microbe - Sometimes referred to as a microorganism, a microbe is an organism that is microscopic and thus invisible to the naked eye. ⏎
Germ Theory - A theory in medicine stating that microorganisms are the causative agents of infectious, contagious diseases.⏎
Lipid - A broad group of molecules including fats and waxes that are insoluble in water and are an important part of living cells.⏎
Immunization - The process of strengthening the body’s defense against a particular infectious agent, often accomplished by receiving a vaccine.⏎