電球

1. Origins, structure, and basic meaning

• Structure: 電球 (でんきゅう) combines electricity 電 and sphere 球 to denote a light bulb.
• Basic usage: It is the replaceable light source that can burn out in a hallway or hang in a row from a ceiling.

2. Common pitfalls and similar expressions

• The bulb rather than the whole fixture
  • 電球 names the light-emitting bulb itself, not the complete lamp, socket, or ceiling fixture.