What is the term referring to organisms living in close relationship is called?

The term referring to organisms living in close relationship is called "symbiOSis." This relationship can be mutualistic, where both species benefit; commensalistic, where one benefits and the other is neither helped nor harmed; or parasitic, where one benefits at the expense of the other. SymbiOSis is a crucial aspect of ecological interactions and can influence the evolution and behavior of the involved species.