Terrestrial spheres refer to the Earth and its surrounding environment. Some synonyms for terrestrial spheres include the biosphere, which comprises all living organisms on Earth; the lithosphere, which covers the Earth's rocky outer layer; the hydrosphere, which includes all the Earth's water bodies; and the atmosphere, which is the Earth's gaseous layer. Additionally, the cryosphere refers to the frozen parts of the Earth's surface, while the pedosphere is the layer of soil and dirt covering the Earth's surface. Overall, terrestrial spheres encompass all aspects of the Earth and provide us with a deep understanding of the planet's intricate systems.