| Term | Definition |
| Antibiotic | a substance used to kill or slow the growth of bacteria or other microorganisms. |
| Binary fission | the simple cell division in which one cell splits into two; used by bacteria. |
| Bioremediation | the use of bacteria and other microorganisms to change pollutants in soil and water into harmless chemicals. |
| Endospore | a bacterium surrounded by a thick, protective membrane. |
| Host | an organism on which a parasite lives. |
| Pathogenic bacteria | bacteria that invade a host organism and obtain the nutrients they need from the host's cells. |
| Virus | a microscopic particle that invades a cell and often destroys it. |