Terrestrial means related to Earth or land, as opposed to water, air, or space. When scientists talk about terrestrial planets like Earth, Mars, or Venus, they mean rocky planets with solid ground, unlike gas giants like Jupiter. A terrestrial animal is one that lives primarily on land: tigers, elephants, and rabbits are terrestrial, while whales and dolphins are not.

You might hear about terrestrial life when scientists discuss the possibility of life on other planets, distinguishing creatures that live on Earth from any extraterrestrial life that might exist beyond our world.

In everyday usage, terrestrial can also describe the ordinary, earthbound quality of something. Terrestrial concerns might mean practical, everyday matters like homework or chores, as opposed to lofty, abstract ideas. When astronomers spend their days studying distant galaxies but still need to remember to buy groceries, those grocery trips are their terrestrial responsibilities, the down-to-earth tasks that keep life running smoothly while they explore the cosmos in their minds.