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light bulb

/ˈlaɪtˌbʌlb/noun

light bulb is a noun meaning “An evacuated glass bulb containing a metal filament which is heated by electrical resistance to produce light” (English Wiktionary, September 2026). It is spelled L-I-G-H-T-B-U-L-B. The plural of light bulb is light bulbs or light-bulbs.

What does light bulb mean?

noun

  1. 1

    An evacuated glass bulb containing a metal filament which is heated by electrical resistance to produce light.

  2. 2

    An article that resembles such a bulb and converts electricity to light by any process.

    a fluorescent light bulb

  3. 3

    Used in reference to the sudden arrival of a realization, an inspiration, an idea, or the like.

    a light-bulb moment

noun

as light-bulb
  1. 1

    Alternative form of light bulb.

Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).

How do you pronounce light bulb?

  • /ˈlaɪtˌbʌlb/

Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract). Recordings: LL-Q1860_(eng)-Vininn126-light_bulb.wav, Wikimedia Commons (author and licence on each file's page).

Forms of light bulb

  • light bulbs plural
  • light-bulb
  • lightbulb
  • light-bulbs plural

Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).

Words people confuse with light bulb

Word pairs people search, with the monthly searches for “a vs b” (G: Google, B: Bing, United States).

light bulb vs lightbulb0 B

Also written: lightbulb (one word or two).

Sources: Google and Bing searches (September 2025 to August 2026, through DataForSEO); English Wiktionary (homophones, alternative spellings).

Light bulb in Spanish, French, German and Portuguese

In the sense evacuated glass bulb containing a metal filament that produces light:

LanguageWords
Frenchampoule, lampe, ampoule électrique
GermanGlühbirne, Glühlampe, Birne
Portugueselâmpada, foco, bulbo
Spanishampolleta, bombilla, bombillo, bujía, foco, lamparita

Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract). Translations are Wiktionary's, by sense; a linked word has its own PlainSpell page.

Where does light bulb come from?

From light + bulb First attested in 1885.

Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).