playground

noun3

1. •
   A large open space for children to play in, usually having dedicated play equipment (such as swings and slides).

   • The kids have to go to the playground during recess, no matter the weather.
   • The local council have set up a new playground, equipped with slides, swings, and a climbing wall.
2. •
   (figurative) Any physical or metaphysical space in which a person or organization has free rein to do as they please.

   • The exclusive tropical island was a millionaire's playground.
3. •
   A sandbox for testing calls to an application programming interface.