General synonyms:
* Environment: This refers to the surroundings or conditions in which a person, animal, or plant lives or operates.
* World: This is a broader term encompassing everything that exists.
* The outdoors: This specifically refers to the natural world outside of human-built environments.
* The wild: This refers to areas of nature that are not domesticated or cultivated.
* The natural world: This emphasizes the non-human aspects of the universe.
More specific synonyms:
* Flora: This refers to the plant life of a region.
* Fauna: This refers to the animal life of a region.
* Ecosystem: This refers to a community of living organisms and their physical environment.
* Habitat: This refers to the natural home or environment of an animal, plant, or other organism.
* Wilderness: This refers to a wild and unpopulated area.
The best synonym for "nature" will depend on the specific meaning you are trying to convey.