Terrestrial refers to something related to the Earth, its inhabitants, or its surface. Here are some common uses:

* Terrestrial animals: Animals that live on land, as opposed to aquatic animals.

* Terrestrial planets: Planets that are primarily composed of rock and metal, like Earth and Mars.

* Terrestrial ecosystems: Ecosystems that exist on the Earth's surface, such as forests, grasslands, and deserts.

* Terrestrial radio waves: Radio waves that travel through the Earth's atmosphere, as opposed to those that are sent into space.

Let me know if you had something else in mind!