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

If that switch is exposed to ultraviolet light, the adhesive gives out and releases the spring, closing the circuit and allowing an indicator light bulb to illuminate. —New Atlas, 15 Dec. 2025

Items that can be dropped off include aerosol cans, automotive fluids, automotive and household batteries, bathroom cleaners, carpet cleaners, cooking oil, drain cleaners, fertilizers, paint, light bulbs, and pesticides. —Debra Skodack, Kansas City Star, 10 Dec. 2025

Factories are regularly inundated with buyer requests to make their processes more energy efficient by changing light bulbs, upgrading outdated machinery or installing solar panels, all of which comes with a hefty initial monetary outlay. —Jasmin Malik Chua, Sourcing Journal, 1 Dec. 2025

The change is fantastically small—the equivalent of removing a single light bulb from a board of 10,000 of them, according to Natalie Batalha, former Kepler mission director. —Jeffrey Kluger, Time, 1 Dec. 2025

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