World

When people say "the world" they usually mean Earth, especially in a cultural and geopolitical sense. Humans and all other known living things live in this world. Sometimes "world" means another planet.

Before people discovered that Earth is a planet, they often used "World" to mean "Universe". They still sometimes use it to mean all humans or all civilization.

Sometimes they mean a small part of Earth such as Western world, Islamic world, third world, new world or ancient world.