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

On the other hand, more than two dozen countries have managed to grow their economies without increasing emissions, and the global adoption of wind and solar energy has helped avoid billions of metric tons of emissions. — Simmone Shah, Time, 10 Nov. 2026

The cynic in me delights at how Elon Musk piddled away more than $450 million of his billions on all those losing Republican candidates. — Sun Sentinel Editorial Board, Sun Sentinel, 10 Nov. 2026

The Biden administration awarded billions to Micron via the 2022 CHIPS Act to help fund chip-making plants in Boise and New York, according to previous Statesman reporting. — Idaho Statesman, 10 Nov. 2026

Investors poured billions into multi-family real estate in 2021 and 2022, with many of those loans financed with a 10-year Treasury at around 1%. — Robert Frank, CNBC, 10 Nov. 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