1
US : a number equal to 1,000 million see Table of Numbers
also, British : a number equal to 1,000 milliard see Table of Numbers
2
: a very large number
billion adjective

Did you know?

How much is a billion? It might depend on whom you ask. Billion was borrowed from French in the late 1600s to indicate the number one million raised to the power of two, or a million million—a number represented by a 1 followed by 12 zeros. However, the French later changed their naming conventions so that a billion became a thousand million (a 1 followed by 9 zeros) and a trillion became a thousand thousand million (or a million million, the old billion). The French have since returned to the older system, but it was this new system that was adopted by American English speakers in the 1800s. In Britain, the newer system has seen increasing use since the 1950s, but the older sense is still sometimes used there as well.

Examples of billion in a Sentence

We could see a billion stars in the sky.
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Layoffs, furloughs or a spending freeze may all be back on the table in January as the next school board inherits a district with billions of dollars in long-term debt that only this summer closed a $732 million deficit. — Alice Yin, Chicago Tribune, 4 Nov. 2026 The measure, which supporters claim would raise tens of billions of dollars, would direct the funds toward healthcare, food assistance programs and education. — Ian McKinney, CBS News, 3 Nov. 2026 This is considerably smaller than supermassive black holes that dominate the hearts of all modern galaxies with masses millions to billions of times the mass of our star. — Robert Lea, Space.com, 3 Nov. 2026 The Legislative Analyst’s Office, the California legislature’s nonpartisan fiscal and policy advisor, estimates the tax would generate tens of billions of dollars in revenue. — ABC News, 3 Nov. 2026 See All Example Sentences for billion

Word History

Etymology

French, from bi- + -illion (as in million)

First Known Use

1801, in the meaning defined at sense 2

Time Traveler
The first known use of billion was in 1801

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Cite this Entry

“Billion.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/billion. Accessed 5 Nov. 2026.

Kids Definition

1
: a number equal to 1,000 million : 1,000,000,000 see number
2
: a very large number
billion adjective
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