A biological system is a collection of living organisms and their surrounding environment, which together function as a unit. There are several synonyms for this term, including "ecosystem," which refers to the interaction between living organisms and their physical surroundings. Other synonyms include "biosphere," which encompasses all of the living organisms on Earth, and "microbiome," which refers to the collection of microorganisms that inhabit a particular environment. Additionally, the term "anatomy" refers to the physical structures of living organisms, while "physiology" refers to their functions and processes. Ultimately, all of these terms relate to the complex, interconnected systems that keep living organisms alive and thriving.