light bulb

noun

variants or lightbulb

ˈlīt-ˌbəlb 

plural light bulbs or lightbulbs

: an electric lamp: such as

a

: one in which a filament gives off light when heated to incandescence by an electric current

called also incandescent, incandescent lamp

b

: one having a coating of fluorescent material on its inner surface that emits visible light : fluorescent lamp

especially : compact fluorescent light

c

: one using LEDs to generate light

Illustration of light bulb

• 1 bulb containing gas
• 2 filament
• 3 connecting and supporting wires
• 4 exhaust tube
• 5 screw base
• 6 base contact

Examples of light bulb in a Sentence

Recent Examples on the Web

Finally, the light bulb went off. —Michael Russo, New York Times, 20 Feb. 2026

There was a metal cot, a coal-burning stove and a bare light bulb hanging from the ceiling. —Zoe Sottile, CNN Money, 16 Feb. 2026

Here, interior designers share how to use lighting to beat mid-winter blues, which can be as simple as switching out a light bulb. —Shagun Khare, The Spruce, 15 Feb. 2026

One of my favorite all-time estate sale finds was a huge box filled with a variety of light bulbs for $5. —Jennifer Prince, Southern Living, 15 Feb. 2026

Word History

First Known Use

1885, in the meaning defined above

Rhymes for light bulb

• lightbulb

Kids Definition

lightbulb

noun

light·​bulb ˈlīt-ˌbəlb 

: an electric lamp: as

a

: one in which a filament gives off light when heated by an electric current

called also incandescent lamp

b

: fluorescent lamp