A filament surrounded by glass which is screwed into the socket of a lamp and which emits light when supplied with current.
a glass bulb containing a wire filament (usually tungsten) that emits light when heated
electric lamp consisting of a glass bulb containing a wire filament (usually tungsten) that emits light when heated
electric lamp consisting of a transparent or translucent glass housing containing a wire filament (usually tungsten) that emits light when heated by electricity