The term 'light bulb' can be broken down into two crossword solutions: GLOBE (5 letters) and IDEA (4 letters). A light bulb is a device that produces light when electricity passes through it. It consists of a glass GLOBE filled with a gas, usually argon or nitrogen, and a filament made of tungsten wire. When electricity passes through the filament, it heats up and produces light. The IDEA of a light bulb was first proposed by Thomas Edison in 1879, and since then, it has become an essential part of modern life.