The pocket in your pants or jacket is a small pouch sewn into clothing where you can carry things like keys, coins, or a favorite rock you found. Pockets are one of those inventions that seem so obvious you'd think they've always existed, but they only became common features in clothing a few hundred years ago. Before that, people carried small bags tied to their belts.

The word describes other small spaces too. A pool table has pockets at each corner where balls drop in. A kangaroo carries its baby in a natural pocket called a pouch. When you find a pocket of warm water while swimming, you've discovered a small area that feels different from its surroundings.

Pocket also works as an adjective for small versions of things: a pocket dictionary fits easily in your bag, and pocket money (also called an allowance) is the small amount of cash kids might receive for doing chores.

You can pocket something by putting it in your pocket, though this word sometimes suggests keeping something you shouldn't have. If a cashier pockets extra change instead of putting it in the register, that's stealing. But if you pocket your pride and apologize after an argument, you're setting aside your ego to do the right thing.