billion

noun

bil·​lion ˈbi(l)-yən 

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

billionth

ˈbi(l)-yən(t)th 

adjective or noun

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

The report highlights that even as fiber lines are extended into rural areas and billions of federal and state dollars are deployed, affordability and access remain insurmountable barriers for many families. — Erin Mote, Forbes.com, 15 Sep. 2026

On one side of the debate are fears that older chips, which serve as collateral for billions of dollars of borrowing by neoclouds like CoreWeave and underpin data-center deals, will become obsolete and decline in value. — Reed Albergotti, semafor.com, 15 Sep. 2026

Other scientists go bottom-up, mimicking in a lab what Earth’s environment might have been like billions of years ago to try to produce the complex chemistry that became biology, as Miller and Rheinstädter have done. — Sarah Scoles, Scientific American, 15 Sep. 2026

Texas hands out billions in tax abatements and incentives to mega-corporations that often fail to deliver lasting benefits to local communities. — Eleanor Dearman, Fort Worth Star-Telegram, 15 Sep. 2026

Word History

Etymology

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

First Known Use

1801, in the meaning defined at sense 2

Phrases Containing billion

• never/not in a thousand/million/billion years

Rhymes for billion

• million
• pillion
• trillion
• castilian
• civilian
• cotillion
• pavilion
• postilion
• quadrillion
• reptilian
• vermilion
• vermillion

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Kids Definition

billion

noun

bil·​lion ˈbil-yən 

1

: a number equal to 1,000 million : 1,000,000,000 see number

2

: a very large number

billion adjective

billionth

-yən(t)th 

adjective or noun