The top or cover of a container.

(slang) A cap or hat.

(slang) One ounce of cannabis.

(surfing, slang, chiefly Australia) A bodyboard or bodyboarder.

(slang) A motorcyclist's crash helmet.

(slang) In amateur radio, an incompetent operator.

Clipping of eyelid.

(microelectronics) A hermetically sealed top piece on a microchip such as the integrated heat spreader on a CPU.

(figurative) A restraint or control, as when "putting a lid" on something.

(Liverpool) A kid (from the rhyming slang bin lid)

(transitive) To put a lid on (something).