Evolution - The change in heritable traits in a population of organisms over successive generations.⏎
Cytokine - A type of protein secreted by cells in the immune system that carries signals that facilitate cell-to-cell communication and help regulate the way the immune system responds to inflammation and infection.⏎
Epidemic - An often sudden increase in the level of disease in a specific population over a given period of time.⏎
Ecology - A branch of science that deals with the relation of organisms to one another and their physical environment.⏎