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.
Sabbagh predicts this could transform the space industry from having less than 10 million users of mobile satellite services to being able to reach billions of users. — Melissa Hancock, Fortune, 21 Oct. 2026 Meeting global climate goals will probably require pulling billions of metric tons of CO₂ from the atmosphere annually by mid-century, according to the United Nations. — Alec Luhn, Scientific American, 20 Oct. 2026 Over billions of years, gravity amplified these small density variations, helping produce the large-scale cosmic web of galaxies and dark matter observed today. — Kaif Shaikh, Interesting Engineering, 20 Oct. 2026 But the legacy carriers get billions each year from banks that issue their popular reward cards. — The Week Us, TheWeek, 20 Oct. 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 22 Oct. 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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