- 1[countable] a large round object in space that moves around a star (such as the sun) and receives light from it the planets of our solar system the planet Earth/Venus/Mars
- 2 the planet [singular] used to mean “the world,” especially when talking about the environment the battle to save the planet Idioms
nounjump to other results
used to suggest that someone's ideas are not realistic or practical He thinks being a father is easy. What planet is he on?
to be on another planet, what planet is somebody on? (informal) (humorous)jump to other results