There isn't one perfect single noun that captures all aspects of "environment". Here are some options, depending on the specific context:

General:

* Surroundings: This is a broad term that encompasses everything around a person or thing.

* Habitat: This refers to the natural environment where a particular organism lives.

* Ecosystem: This emphasizes the interconnectedness of living things and their physical environment.

* Biosphere: This is the global sum of all ecosystems.

Specific:

* Atmosphere: The air surrounding the Earth.

* Biota: The collection of living organisms in a region.

* Flora: The plant life of a region.

* Fauna: The animal life of a region.

* Landscape: The physical features of a region.

* Terrestrial: Refers to the land environment.

* Aquatic: Refers to the water environment.

The best noun to use depends on the specific meaning you want to convey.