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

With plenty of surface area for your alarm clock and current read, this nightstand features a round light bulb that rests in a slight divot. —Kate McGregor, Architectural Digest, 27 Feb. 2026

Attention should also be paid to curtains, mirrors, lampshades and light bulbs that tend to gather dust. —Bestreviews, Chicago Tribune, 27 Feb. 2026

But the electricity of the moment turned on a light bulb for Weissman. —Mike Sutter, San Antonio Express-News, 25 Feb. 2026

And the hope for the Warriors is that the case-in-point success of Sunday will keep the light bulb on. —Dieter Kurtenbach, Mercury News, 23 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