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

Patel arrived in Jakarta shortly after talks with Cambodian Prime Minister Hun Manet concerning joint efforts to combat international online scam operations that cheat victims out of billions of dollars annually. — ABC News, 23 July 2026

Silicon Valley residents are increasingly trying to stop the advance of artificial intelligence, even as the region attracts hundreds of billions of dollars in investment to expand the technology’s reach. — Queenie Wong, Los Angeles Times, 22 July 2026

Vehicle manufacturers promised all-electric lineups, spent billions on engineering, and told investors that gasoline was dead—internal combustion engines were going the way of dinosaurs. — Michael Harley, Forbes.com, 22 July 2026

It's expected to last decades and be worth billions of dollars, the Energy Department said. — Geoff Brumfiel, NPR, 22 July 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

Podcast

Get Word of the Day delivered to your inbox!

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