billion

American  

[bil-yuhn] / ˈbɪl yən /

noun

plural

billions,

plural

billion

1. a cardinal number represented in the U.S. by 1 followed by 9 zeros, and in Great Britain by 1 followed by 12 zeros.

2. a very large number.

   I've told you so billions of times.

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adjective

1. equal in number to a billion.

billion British  

/ ˈbɪljən /

noun

1. one thousand million: it is written as 1 000 000 000 or 10 ⁹

2. (formerly, in Britain) one million million: it is written as 1 000 000 000 000 or 10 ¹²

3. (often plural) any exceptionally large number

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determiner

1. (preceded by a or a cardinal number)

   1. amounting to a billion

      it seems like a billion years ago

   2. ( as pronoun )

      we have a billion here

Other Word Forms

• billionth adjective

Etymology

Origin of billion

1680–90; < French, equivalent to b ( i )- bi- ¹ + -illion, as in million

Compare meaning

How does billion compare to similar and commonly confused words? Explore the most common comparisons:

• billion vs. trillion

Explanation

A billion is 1,000,000,000. There are over 7 billion people in the world, the last time we checked. While billion may sounds like a made-up number like zillion — which just means a lot — it's a very real number, specifically 1,000,000,000. That's a pretty hard number to imagine, but one way to think of it is as a thousand millions. If you have a billion dollars, you're very rich: a billionaire. Money spent by the government is often measured in billions. In England, this word often refers to a different number: 1,000,000,000,000, or one million millions.

Example Sentences

Token use in OpenAI’s API—a platform where mostly enterprise users access its software—rose from six billion a minute in October to 15 billion a minute in late March.

From The Wall Street Journal • Apr. 13, 2026

Meanwhile, OpenAI’s projections for data-center spending suggest the company may run losses of almost $250 billion through 2029.

From The Wall Street Journal • Apr. 12, 2026

Linenberg sees the industry earning $11.5 billion in operating profit this year, down from $20 billion before the war.

From Barron's • Apr. 12, 2026

Linenberg sees the industry earning $11.5 billion in operating profit this year, down from $20 billion before the war.

From Barron's • Apr. 12, 2026

Thus Howie Hubler’s personal purchase of $16 billion in triple-A-rated CDOs dwindled to something like $13 billion.

From "The Big Short" by Michael Lewis