A lining is a layer of material attached to the inside of something to protect it, make it stronger, or improve how it works. Your winter coat probably has a soft lining that keeps you warm and prevents the scratchy outer fabric from touching your skin. A jewelry box might have a velvet lining to protect delicate treasures from getting scratched.

The word appears in some common expressions. When people say “every cloud has a silver lining,” they mean that even bad situations have some good aspect if you look for it. If someone is accused of lining their pockets, it means they're secretly taking money they shouldn't have, like a dishonest official enriching themselves through their position.

Linings show up everywhere once you start noticing them: the fabric inside shoes, the coating inside cans to prevent rust, or the membrane inside an eggshell. Engineers and designers add linings to solve specific problems, whether it's keeping heat in, moisture out, or making something more comfortable. That comfortable pair of sneakers you love? Thank the lining that cushions your feet and helps wick away sweat.