To put a lid on (something).
A hermetically sealed top piece on a microchip such as the integrated heat spreader on a CPU.
In amateur radio, an incompetent operator.
A cap or hat.
One ounce of cannabis.
A restraint or control, as when "putting a lid" on something.
A kid (from the rhyming slang bin lid)
A bodyboard or bodyboarder.
The top or cover of a container.
A motorcyclist's crash helmet.