Epidemic - An often sudden increase in the level of disease in a specific population over a given period of time.⏎
Ecosystem - A functional unit that consists of all the living organisms in a particular area, as well as the nonliving, physical components in the environment—such as air, soil, water, and sunlight—with which the organisms interact, and how natural and human-made changes affect these interactions.⏎
Fertilized Egg - Sometimes referred to as a zygote, this is the resulting initial cell formed when a sperm cell unites with an egg cell.⏎
Egg Cell - The female gamete, or sex cell, which carries the hereditary material of the female parent and unites with the male sperm cell during sexual reproduction.⏎