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

During a Senate Finance Committee hearing in Juneau this spring, Morrison presented lawmakers with a giant light bulb, blackened by a short in the electrical wiring in the school's gymnasium ceiling. —Emily Schwing, NPR, 17 Nov. 2025

This 15-inch ceramic tree from Best Choice Products is hand-painted with light and dark green accents and features 64 light bulbs that glow in beautiful colors. —Alicia Geigel, Southern Living, 14 Nov. 2025

One light bulb under the main ventilation hood was not working. —Sacbee.com, 7 Nov. 2025

There, a group of KPMG staffers followed and sometimes interjected their own thoughts on the building, while workers fastened the last screws on light bulbs and organized plants strewn around the office. —Eva Roytburg, Fortune, 5 Nov. 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