Other forms: lids
A lid is a top, or a cap — some kind of removable or hinged cover for a container. If you forget to put the lid on your tin of cat food, you may discover that your cat and dog have eaten it all by the end of the day.
The lid on your trash can keeps raccoons out of it, and the lid on your travel mug keeps your tea hot for hours. Another lid is your eyelid, the skin that moves over your eyeball like a lid: "Her heavy lids told me she didn't sleep at all." A lid is also slang for a hat or a helmet, and if someone says, "Put a lid on it," they're telling you (somewhat rudely) to quiet down.