any of various devices for producing visible light, e.g.:
a container filled with an inflammable substance, e.g. oil or gas, that is burned to give out artificial light
a usu portable electric device containing a light bulb
any of various light-emitting devices, e.g. a sunlamp, that produce electromagnetic radiation, e.g. heat radiation
[Middle English via French and Latin from Greek lampas, from lampein to shine]